Can't unlock boot of Benz C240 with mechanical key, remote control or fob. What do I do?

you should be able to use the mechanical key that is located on the side of your remote key fob. It slide out.
Then insert it into the lock under the rear lip of the truck near the release handle.
Hope this helps

That sounds like a seized linkage issue. Open door panel and disconnect linkage from the actuator. If the actuator works, it's the linkage

TRY A NEW BATT IN THE KEY FOB.

TRY A NEW BATT IN THE KEY FOB!

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.

Your keyless remote is equipped with 2 different systems. There is the RF system (long range, lock control only) and the IR system (short range, locks and convenience features such as remote window roll-up and roll-down). It sounds like your RF system isn't working. The only way to test the system, that I know of, is with a Mercedes scanner. It is likely a bad remote.

Try checking the key reader it's usually a plastic ring around the key barrel. If it's dies will not read code in key to enable the car to start. Check your key is sending a code as well.

If you mean has remote got a emergency key
Look on top of remote for small catch, slide and pull out key

I have a 2001 C240 with the same issue. I removed the positive battery cable from the battery and kept it off for 30 seconds then replaced it. Everything was reset and the key worked.

VW/AUDI/SEAT/SKODA



Remote Control Programming (1997 ON)

Procedure
1. Switch Ignition ON and leave the key in the ignition.

2. Mechanically lock the vehicle using the Drivers door using a second
key.

3. Using the remote control press the Unlock button once, and the horn
will sound once.

4. Wait 6 seconds and press the unlock button once to activate the coding
procedure. The remote control will now be programmed.

NOTE : When performing programming on additional remotes the procedure
is the same, except you press the unlock button 2, 3 or 4 times for the
different remote.

For example : If programming 2 remotes press the unlock button twice with
a 1 second interval between each press, repeat for 3 and 4 remotes.

5. Switch Ignition OFF.

6. Remove key from ignition and check for operation.

7. The coding procedure can be repeated up to 4 times for additional remotes.

8. The ignition must be switched OFF between programming each remote
control.

Remote Control Erasing (1997 ON)

Procedure
1. Switch Ignition ON and leave the key in the ignition.

2. Mechanically lock the vehicle using the Drivers door using a second
key.

3. Press the remote control unlock button 5 times in 1 second intervals.
A short horn will sound.

4. Wait 6 seconds and press the unlock button once to activate memory
erase.

5. Switch ignition OFF, all remotes are now erased.