Following a flat battery on my S Class I am now getting a Do Not Drive message and all 4 hazards indicators are flashing

Probably the switch input to the BCM is bad . door ajar switch .
The BCM is also capable of commanding other vehicle systems to control functions that are not directly wired to and/or controlled by the BCM. The BCM accomplishes this task by sending specific messages on the class 2 serial data link. The vehicle system capable of performing such function will respond to the BCM message.
The BCM controls/monitors the following functions:
• Audible warnings
• Indicators control
• Interior lighting
• Exterior lighting
• Power/automatic door locks
• Keyless entry
• Content theft deterrent
• Personalization
• Serial Power Modes
• Electrical Power Management

Audible Warning
The body control module (BCM) provides the following audible control functions. Some audible control functions may be controlled by other systems through the class 2 serial data link:
• Headlamp on reminder
• Key in ignition reminder
• Personalization mode
• Delay locking indication
• Keyless entry programming/diagnostic mode indication

Indicator Control
The body control module (BCM) provides the following indicator control functions through the class 2 serial data circuits. Some indicator control functions may be controlled by other systems through the class 2 serial data link:
• Door ajar
• Liftglass/endgate ajar
• Park brake
• High beam
• Park lamp malfunction
• Service vehicle soon
• Personalization mode
• Security LED
• Battery

Door Locks Go Crazy 1
Door Locks Go Crazy 2
Door Locks Go Crazy 3

The body control system consists of the following 3 modules:
• The Dash Integration Module (DIM)
• The Instrument Panel Module (IPM)
• The Rear Integration Module (RIM)
Each of the 3 body control modules integrate a number of functional systems under the control of a single module. Each module is connected to the Class 2 serial data circuit, many of the control functions are implemented by Class 2 messages.

What system (S) are you having problems with ?
Rear Integration Module (RIM)
The various RIM inputs and outputs are described in the corresponding functional areas as indicated on the RIM electrical schematics.
The RIM functions include the following:
• Automatic level control
• CIGAR relay control
• Class 2 communication requiring RIM interaction
• Content theft deterrent
• Fuel door control
• Fuel level sensor input
• Heated seat control
• HVAC blower control
• LK/CYL relay control
• Park brake relay control
• Rear defog relay control
• Rear park assist chime control
• Retained accessory power (RAP) relay control
• Reverse relay control
• Transmission shift inhibit
• Trunk release relay control
• Various controls for the interior lamps

Instrument Panel Integration Module (IPM)
The various IPM input and output circuits are described in the corresponding areas as indicated on the IPM electrical schematics.
The IPM functions include the following:
• 54 volt VF display input
• Ambient light sensor input
• Class 2 communication requiring IPM interaction
• Fog lamp switch inputs
• Front HVAC air delivery controls
• Front HVAC sensor inputs
• Front HVAC temperature controls
• Fuel door and rear compartment lid release switch input
• Hazard switch input
• HUD active control
• Instrument panel lamps dimmer switch input
• Ignition switch headlight control
• Interior lamps switch input
• Key in ignition switch input
• Traction control switch input
• Twilight sentinel delay input

Dash Integration Module (DIM)
The various DIM input and output circuits are described in the corresponding functional areas as indicated on the DIM electrical schematics.
The DIM functions include the following:
• Class 2 communication requiring DIM interaction.
• Control of exterior lamps.
• Control of front fog lights.
• Control of the headlights.
• Headlamps on with wiper input.
• Hood ajar switch input w/export.
• Horn relay control.
• Interior lamps incandescent dimming.
• Low side temperature for HVAC compressor.
• Power moding control over Class 2 serial data circuit.
• Reverse lockout solenoid control.
• Steering wheel controls input.
• Storage of the clock settings and, sending a message out on the class 2 serial data circuit in response to requests from other modules.

Doesn't have one ! The electronic brake control module turns it on an off when there is a problem ! Your light on ? DTC'S - diagnostic trouble codes stored .
Traction Off
The IPC illuminates the traction off indicator when the following occurs:
• The electronic brake control module (EBCM) inhibits the traction control system. The IPC receives a class 2 message from the EBCM requesting illumination. The traction control system is disabled when the following occurs:
- For Chevrolet only, the shift lever is in FIRST (1) or SECOND (2) gear. The EBCM receives a class 2 message from the powertrain control module (PCM) indicating the gear position.
- For Pontiac and Oldsmobile only, the body control module (BCM) detects that the traction control switch is pressed (signal circuit is low). The EBCM receives a class 2 message from the BCM indicating the switch status.
- The BCM detects that the park brake is engaged (signal circuit is low) and that the engine is on. The EBCM receives a class 2 message from the BCM indicating the park brake status.
- The PCM detects certain malfunctions and is unable to perform torque reduction requests from the EBCM. The EBCM receives a class 2 message from the PCM indicating that traction control cannot be performed.
• The EBCM detects a malfunction in the traction control system. The IPC receives class 2 messages from the EBCM requesting illumination of both the service vehicle soon and traction off indicators.
• The IPC performs the displays test at the start of each ignition cycle. The indicator illuminates for approximately 3 seconds.

How many mile are on you vehicle ? Have you ever had Alternator replaced before ? You alternator maybe starting to fail , brushes or the voltage regulator .
Charging System Indicators
BATTERY The IPC illuminates the battery indicator when the following occurs:
?€¢
The PCM detects that the generator output is less than 11 volts or greater than 16 volts. The IPC receives a class 2 message from the PCM requesting illumination.

?€¢
The IPC determines that the system voltage is less than 11 volts or greater than 16 volts. The IPC receives a class 2 message from the body control module (BCM) indicating the system voltage.

?€¢
The IPC performs the displays test at the start of each ignition cycle. The indicator illuminates for approximately 3 seconds.

?€¢
The ignition is on, with the engine off.
BATTERY NOT CHARGING The IPC illuminates the battery not charging indicator in the driver information center when the following occurs:
?€¢
The PCM detects that the generator output is less than 11 volts or greater than 16 volts. The IPC receives a class 2 message from the PCM requesting illumination.

?€¢
The IPC determines that the system voltage is less than 11 volts or greater than 16 volts. The IPC receives a class 2 message from the body control module (BCM) indicating the system voltage

It would be a good idea to have it checked out , most auto parts stores will do this for free !

You checked the charging voltage at the battery with a ? volt meter ? What was the voltage with the vehicle running ? 13.1 to 14.1 volts ?
BATTERY NOT CHARGING The IPC illuminates the battery not charging indicator in the driver information center when the following occurs:
?€¢
The PCM detects that the generator output is less than 11 volts or greater than 16 volts. The IPC receives a class 2 message from the PCM requesting illumination.

?€¢
The IPC determines that the system voltage is less than 11 volts or greater than 16 volts. The IPC receives a class 2 message from the body control module (BCM) indicating the system voltage

Charge Indicator Always On
Step
Action
Yes
No

1

Did you perform the Diagnostic System Check for Starting and Charging? yes or no
Go to Step 2 yes
Go to Diagnostic System Check - Engine Electrical no

2

1. Turn ON the ignition, with the engine OFF.
2. Observe the Charge indicator on the instrument cluster (IPC)

Does the charge indicator illuminate?
Go to Step 3
Go to Symptoms - Engine Electrical

3

1. Turn OFF the ignition.
2. Disconnect the generator connector.
3. Turn ON the ignition, with the engine OFF.

Does the charge indicator illuminate?
Go to Step 4
Go to Charging System Test

4

Test the charge indicator control circuit for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?
Go to Step 6
Go to Step 5

5

Replace the PCM. Refer to Powertrain Control Module Replacement in Engine Controls 4.2L.
Did you compete the replacement?
Go to Step 6
--

6

Operate the system in order to verify the repair.
Did you correct the condition?
System OK
Go to Step 3

WHEN SERVICE ELEC SYSTEM IS FLASHING. PLEASE CHECK FOLLOWING:-

1. Check for a voltage drop to the Power Train Control Module (PCM) and Electronic Brake Control Module (EBCM) when the problem is happening.

2. If the voltage is less than Battery Voltage (B+) when the problem happens check for a voltage drop through the ignition switch. Tech Tips: SERVICE ELECTRICAL SYS - 106
The IPC illuminates the SERVICE ELECTRICAL SYS -- 106 message in the DIC when one of the following conditions exist:

• The Dash Integration Module (DIM) detects a malfunction that is related to the ignition switch.

The IPC receives a class 2 message requesting illumination from the DIM.

• There is a Powertrain related code present.

The IPC receives a class 2 message requesting illumination from the PCM.

Conditions for Setting the DTC P1574
A 2.5 mph or greater decrease in non-drive wheel speed in 0.4 second and extended travel brake switch or TCC brake switch indicating brakes applied and no transition noticed in the stop lamp contacts of the stop lamp switch.
ALSO CHECK FOR FAULT CODES IN THE OBD.

I’m happy to assist further over the phone at https://www.6ya.com/expert/uttamjeet_2f3adc18600f8ede

The AU ford has two indicator relays , turning lights and hazard lights ,both use the indicator lights ,the hazards flash both front and rear lights , the turning indicator flashes one front and one rear light. I think the fault may be in the hazard circuit.

Maybe you need a new battery

Did you have it tested

Do you know how old it is
or how many times it went flat

did you change the battery ? wrong amps or voltage could do that sometimes. it's called reverse polarity.

Ok this is very easy to do :
1- Switch ignition on. 2- make sure the standard display menu appears in the multifunction display. 3- Press button down or up repeatedly until the following message appears in the multifunction display
RUN FLAT INDICATOR
ACTIVE
REACTIVATION POSS.: +

4- Press "+" 5- The following message will appear in the display
TIRE PRESSURE OK NOW?

6- To confirm activation press "+" 7- The following message will appear in the display
RUN FLAT INDICATOR
REACTIVATED

8- Wait till "TIRE PRESSURE OK NOW?" disappears
You are done
Hope this helps