Cant reach battery
 

I have a 1980 SLC 450 Mercedes.
I have the door key and the key starter.
The problem I have is I can not get in the trunk with the key.
The battery is dead, and the battery is in the trunk.
Is there any way I can jump the car from the front in this model?
I saw something like looks similar to a post in front electric box, (box wont open either)!

Any help would be appreciated.

new to this ,so not familiar with that vehicle,that said,use a trickle charger and charge the battery through the cigar lighter.Of course the wiring wont handle the current required to Jump start the engine.

can you take apart the back seat
 

can you take the back seat out in the back of your car
by lifting it or ask a mechanic on this post directly