Key fob stopped working, opened doors manually but ignition not working everything dead , changed battery's in both keys charged battery started 1st time tried again later same problem completely dead

Try this

To fix the Dodge Nitro anti-theft mechanism, you will insert the ignition key and turn it to the on spot, and then attempt to start the engine (crank over), the engine does not run. With the key still in the run spot, wait 10 minutes, and the safety light will flash and then go out.

How do i reset the Dodge Nitro anti theft? - Vehicle History

Or this

How do I reset my Dodge anti-theft system?
To deactivate the anti-theft system so that you can drive your vehicle normally once again, the steps are simple:

1. Place your key in the ignition of the vehicle.
2. Do not attempt to crank up your truck.
3. Allow your key to sit in the ignition for 60 seconds. ...
4. After 60 seconds have passed, start your vehicle as normal.

Jun 28, 2021

Dodge Ram 1500: Resetting the Anti Theft - VehicleHistory

i cant guess what battery was changed
in the FOB or in the CAR? under hood. battery?????
my wild guess is this
you turn the key to ON
and the dash does not light up, no warnings?
or you turn the key and it does that but there
is no cranking sounds from the engine... area.
what?

try a better post
I try to start my car, with the key and it will not crank
or, i try to start my car, with the key but it cranks fast but will not start
and win.

The key blade is to open drivers door and glove box only, you did not specifie what model and year of car you have. on most smart key Nissans there should be a port to put the fob in if fob battery is dead

you need a full charged battery or battery replaced [if battery bad and not holding charge] your remote key fob will not work if battery is dead or to weak to start car but key should be able to manually open drivers door --if its not an original key new cut or worn down [may have to jiggle in door ] your anti theft/security lock will come on when you use key in door than you have a few seconds after you open door to put key in ignition and turn to on position before alarm goes off but you need to get battery issue corrected first if key still doesnt work may need to have assistance [slimjim]lock to get in

This model year comes equipped with Keyless Enter-N-Go, which uses an electronic transmitter in the key fob to communicate with the car. The vehicle's doors will not unlock and the vehicle will not start if the key fob is not matched to the vehicle or if the commonly-available watch battery in the key fob has been depleted. The EVIC will flash a message upon vehicle startup if it determines that the battery in your key fob is low on charge and should be replaced.

To open the doors, try the following:

1. Use the spare key fob that came with the vehicle. If the battery in your main key fob is depleted, the spare key fob's battery may still retain charge due to its much more occasional use.

2. The key fob comes with an emergency key inside of it. To remove the emergency key, slide the mechanical latch on the back of the key fob sideways with your thumb and then pull the key out with your other hand. This key will allow you to unlock the driver's side door and glove compartment. It will not start the vehicle.

To start the car with a severely-depleted key fob battery, try the following:

1. In case the ignition switch does not change with the push of a button, the RKE transmitter (Key Fob) may have a low or dead battery. In this situation a back-up method can be used to operate the ignition switch. Put the nose side (side opposite of the emergency key) of the Key Fob against the ENGINE START/STOP button and push to operate the ignition switch.

To replace the battery in your key fob, try the following:

1. Remove the emergency key from the key fob following the directions above.

2. Using a vinyl spudger tool or a flat-bladed screwdriver, gently pry the two halves of the key fob apart at the indented slot above the slot for the emergency key.

3. Replace the depleted battery with a new battery. Use the depleted battery to visually match the size. The battery is usually available wherever watch or hearing-aid batteries are sold.

4. Snap the key fob back together and replace the emergency key. If the issue is a depleted battery, your key fob should operate normally.

If the issue is not related to the state of the battery, you will probably need to contact your local dealer for service.

Source: Owner's Manual, pages 12-17

http://justgivemethedamnmanual.com/dodge/dodge-charger-owners-manual/

it has gone into theft mode. you will need to have the system rest. it makes it so the parts are useless. when you take the battery off for any reason you need to have the key in the ignition on number 2 then off to 0. leave key in and you now have 30 seconds to take of the battery. just taking off the battery with out doing this can activate the systerm.

There is a special procedure involved in keying your fob to your car once the battery has been changed. You must lock and open the door with your key. Turn the ignition to "on"(not start) then push the fob's open and close button, then shut off ignition. This procedure is done everything the key battery is changed. Hope this can help you!
------------
Motorcycle Diagnostic Scanner

Assuming the car battery is ok (if not, buy a male to male cigarette lighter at the auto store and connect to another car until charged enough to unlock the doors...but don't try to crank the ignition!). The trunks won't open if the battery went dead with the alarm set because arming the alarm physically locks the releases.

Sounds like the key code is switched off because you replaced the key fob battery. Try unlocking the car manual with the key in the door lock. Then switch the ignition on to reactive the keyless entry. If this does not work, you might also try pressing the fob unlock button with the key in the door lock until the dash led flashes.

Insert key into door barrel or ignition lock and turn key, whilst doing this press the unlock/lock button, the led on the dash should flash to indicate this has initialised the key to the car, then remove key and test operation of remote. If this fails then a new remote plus coding to the car by your dealership is needed