I have a serious problem...

So - I left my car in the garage a few months to spare it the harshness of a Swedish winter.
I was stupid. The reason for this is that I did not think to remove the battery before storing the car.
Now the battery is dead, and I can't seem to get to it because of the placement in the boot. The small metal key in the remote works fine to unlock the door, but the lock in the trunk is completely stuck. I can push the tumbler, but not turn the key either way.

It seems only the electronic release button works - but i have no power! So I thought I should try to connect jumper cables from another car to the "+" location in the engine bay. But it does not seem to do anything, and the key won't even turn in the ignition! I tried to wait a while for the battery to get some charge - no luck. I tried to connect a battery charger overnight - still no luck!

So, please, do you guys have any ideas?

My car: CLK430 - 2000 - w208 - coupe

 

Get a can of spray lube and work that trunk lock over good with it, into the key hole.

Drink a few pints and give the key a try. With suitable pliers gently wiggle the key back and forth. Forcing in 1/4 turn will unlock the trunk. If not

Drink a few more pints spray is moderately and try it again. It works mate

When you get it open do not drive the car the police will get you for drunk driving.

 

Strange, so you can get into your car and engine but when you connect another battery into the engine nothing happens?? Are you connecting correctly by lifting the plastic cover on the right side as you face the engine for the positive, negative is just the engine hook or chasis. This power should allow you to start the car or at least get power to the boot release?

 

when you connect battery to the + under the hood (dont forget to connect to good ground), you should be able to pop trunk

 

Thank you for all replies!
Today I actually managed to open the trunk using the "lock spray/oil and beer"-method. My car with it's *** in the air was a very welcome sight!

However, the battery was leaking acid and seemed to be in a very bad way. So, I bought a fresh new one and installed it. Tha car started immediatly. God - I have missed that sound!

The bad thing is that it now indicates errors in the BAS, ABS and EPS -systems... What do you think I can do about it? Is it just because I switched batteries and the computers went absolutely bananas?

 

you have to reprogram all the systems when you replace battery.

so the windows, the sunroof and the steering angle sensor.
turn the wheel all the way to lock, hold it there. wait. then turn the other direction to lock. hold it there. wait. driving should also clear some of your codes

 

When the battery is replaced, the resulting removal of power, erases the memory settings for the BAS/ABS, power windows and radio code.

This, as well as the reset procedures, are explained in your owner's manual.

For example, to reset the BAS/ABS system, just start the car and then turn the steering wheel, lock to lock (e.g. fully left and right).

As A1EK correctly pointed out, the trunk can be opened, using the center console switch, by connecting 12volt power to a terminal, located inside a plastic box behind the windshield washer fluid container, in the engine compartment (e.g. + to the terminal and - to a good ground).

Happy to hear that GatorMB's "lock spray/oil and beer", finally opened your trunk worked for you.

Both methods should have worked, following is why 'not'.

1. Opening the trunk is via the central locking system, which is pneumatically controlled.

After a flat (i.e. dead) battery condition, upon connecting power to the engine compartment terminal correctly, the center console switch will typically activate the central locking system and open the trunk. Occasionally, there may be a delay, required for the pump to restore the correct pressure.

What then should then occur, is under pneumatic control, the locking catch will release from the strike plate.

2. As a backup, MB provided a method, using the provided mechanical key, to open the trunk.

To use this method, all that is required is to be able to turn the mechanism 45 degrees counter clock wise.

Then push in the key, which moves a lever (e.g. same as the pneumatic system does), that will unlock the catch and release it from the strike plate.

Although I like the couple of beers method, hopefully this note will end the frequent postings regarding, "I can't open my trunk".