The back side panel of my AER Compact Mobile. When I bought it used, it only worked on 110V - attached via normal power cable. The batteries would not charge (indicator LED did not turn on at all). So, I decided to tear it apart and find out which batteries were mounted to finally replace them and make live music!

There are seven easy to remove (in my case) short black screws that you need to unscrew to remove the back panel.

Very good German engineering, the panel comes off completely in one piece and slides out nicely from the amplifier body. Nice!

I uploaded an image of the screwdriver I used. It is important that it is robust and of good quality. Not so much for the screws we just took out, but for all later ones, where you need to take the deeper screws out of the massive wood, you better do.