This is regarding the location of the battery for Audi A8 or L base which is actually located in the rear right side wall of the trunk when standing facing at the back side of the car.
But the problem now is how to open the trunk if the battery is DEAD.
Okey this is it. As per my own experience wherein my 2001 A8L Audi got also a problem since I left and forget to close the light when parking at night time so the battery got discharge and now I can not open the trunk of the car. The only best way is to go inside the car at rear back seat in middle portion. Pull down the the arm rest and there is a box where the medical kit is hidden. You can see the wall that is covered and try to open thru to find out inside the trunk. Of course bring a torch or flashlight to see what is going on inside the trunk. Then use a long rod or stick with a flat screw driver tied at the end because we can not enter inside the trunk due to a small entrance to reach the battery or at the end of the wall to the trunk at back side of the car so that you can unscrew the square shape wall cover on the wall opposite to the key lock if you happen to use the key for opening while standing in front at the trunk that is back of the car.
After removing the wall cover mentioned, then you will see a wire connected to the hook for locking the trunk and while at the present position where you are at the rear back seat inside the car, use the rod with a screw driver still at the end and try to push the wire mounted at horizontal position going to right and BINGO ! YOUR TRUNK IS NOW OPEN. Come out of the car and open freely the trunk at the back of the car and on the right of the wall side, open the lid to see where the is battery located and get it recharge by a series connection or either replace the battery with another New Battery. That s all folks if you can follow my instruction, otherwise I will download a video how to do it to view clearly inside the trunk of our Audi A8. Tnx