MB C240, Parking brake will not release

NOT ABS lamp , right?
the parking brake is adjusted first pre the service manual then
the switch must be adjusted to for closure brake released;
i use volt meter that switch after install and make sure it works
if not RTM read the service manual , on topic

this care is ODD
see this chapter in the service manual if opted day1.

Electronic Parking Brake Description tip if ice berg

Vehicles with the electric parking brake have a switch in the center console, which takes the place of the manual parking brake system, the foot pedal and release handle. In case of insufficient electrical power, the electric parking brake cannot be applied or released.
Occasionally, the electronic parking brake will automatically apply when the vehicle is not moving. The electronic parking brake performs a operational check every 50 key cycles. When this check is being performed, the park brake light on the instrument cluster becomes illuminated. This function does not affect the normal operation of the vehicle.
Electric Parking Brake Control Module The parking brake control module has an internal motor, apply actuator, release actuator, and temperature sensor. The parking brake control module also contains the logic for applying and releasing the parking brake when commanded by the park brake control switch. When the parking brake control module receives a signal from the switch the internal circuit board temperature is checked to verify it is within operating range before the control module performs the requested operation.
The electric parking brake module receives hard wired signals from the apply/release switch and communication enable. The electric parking brake module receives wheel speed sensor signals, engine torque, gear information, brake pedal signal, and etc. through GM-LAN.

AND MORE, LOTS MORE, READ THE MANUAL
PAY LIKE i MUST.

https://eautorepair.net/Marketing/Default.asp

Hi Robert, I'd like to help you; what year make and model of the car are you having problems with? Perhaps you can give me more succinct details- I'm unsure what you mean by "the parking brake light went out".
Or do you mean, the light came ON!?
It's normal for the parking brake light to illuminate when you set the parking brake; and for it to turn off when the parking brake is released.
However, if the parking brake light stays illuminated after releasing the brake, the parking brake cable may need to be readjusted at the linkage, located underneath the car...or a simple adjustment to the parking brake pedal or hand level needs adjustment.
I would bring the car back to the mechanic who made the repair since it should be covered/warrantied

Parking Brake Warning Light - RepairPal

repairpal.com/parking-brake-warning-light

• As long as there are no problems detected in the parking brake system, the parking brake light will stay on until the parking brake is completely released.

When you release the parking brake (while keeping the handle pulled) reach down or use your foot and pull the parking brake pedal up . If the light goes off, the switch needs adjustment

If the ABS brake light is on all the time, it could mean you simply forgot to release the parking (emergency) brake. The brake warning light remains on when the brake is set as a reminder. If the brake warning light remains on when the parking brake is released, then something is amiss.----------------------------------------------------------------------------------
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Brake warning light.

If the light is on all the time, it could mean you simply forgot to release the parking (emergency) brake. The brake warning light remains on when the brake is set as a reminder. If the brake warning light remains on when the parking brake is released, then something is amiss.
In some cases, the brake warning light may remain on if the switch on the parking brake pedal or lever is misadjusted. Nothing is wrong with the brakes and a simple adjustment should fix the problem.
If the brake warning light comes on when you apply the brakes, or is on continuously, it means that hydraulic pressure has been lost in one side of the brake system or that the fluid level in the master cylinder is dangerously low (due to a leak somewhere in the brake system). In either case, the fluid level in the master cylinder should be checked. Adding brake fluid to the master cylinder reservoir may temporarily solve the problem. But if there's a leak, the new fluid will soon be lost and the warning light will come back on.

http://autos.yahoo.com/maintain/repairqa/warning_lights/ques010_0.html

Apply the parking brake with the vehicle parked, engine turned off and transmission in Park. Release the parking brake completely, then apply it again, and ensure that it is fully released. Turn the ignition on, check to see if the Parking brake warning light is on. If it is NOT on, apply the parking brake and check to see if the warning light comes on. If the light come ON wihen the Parking brake is applied,.....fully release the parking brake and check if the warning light goes OFF. If it does NOT go off, then an adjustment is needed at the parking brake switch.

Hello,

If the light is on all the time, it could mean you simply forgot to release the
parking (emergency) brake. The brake warning light remains on when the brake is set
as a reminder. If the brake warning light remains on when the parking brake is
released, then something is amiss.

In some cases, the brake warning light may remain on if the switch on the parking
brake pedal or lever is misadjusted. Nothing is wrong with the brakes and a simple
adjustment should fix the problem.

If the brake warning light comes on when you apply the brakes,
or is on continuously, it means that hydraulic pressure has been lost in one side
of the brake system or that the fluid level in the master cylinder is dangerously
low (due to a leak somewhere in the brake system).
In either case, the fluid level in the master cylinder should be checked.
Adding brake fluid to the master cylinder reservoir may temporarily solve the
problem. But if there's a leak, the new fluid will soon be lost and the warning
light will come back on.

Brake fluid leaks are serious because they may cause the brakes to fail!
So avoid driving the vehicle until the system can be inspected to determine what's
wrong. Leaks can occur in brake hoses, brake lines, disc brake calipers,
drum brake wheel cylinders or the master cylinder itself.
Wet spots at hose or line connections would indicate a leak that needs to be fixed.

Leaking brake fluid can also contaminate the brake linings,
causing them to slip or grab. The uneven braking action that results may cause the
vehicle to veer to one side when the brakes are applied. Brake shoes or pads that
have been contaminated with brake fluid cannot be dried out and must be replaced.

Hope this helps.

System has a fault and needs troubleshooting.