I'm not Hugo, but I can tell you that you've solved half the problem if it powers up but thinks it's in the car. The power socket has another connection that you didn't follow; that's the little switch that the player reads to know it's on AC. I'm not sure how the switch is connected (is it normally open or closed? is it connected to +ve or ground?) You'll need someone who knows the Empeg PCB to tell you where else this appears on the main board, I'm afraid. Once you've found it, you should be able to simulate inserting the plug.

Hmm, you could try inserting the plug (either the real one, or the right size plug with no power), and if the switch is working, this might fix your problem. Worth a try, and I don't think it can hurt.

Also, you say that Hugo fixed a broken track to your socket - was that the track that's connected to the switch? Probably, given that it was to fix the "always-at-home" symptom. So that might be a clue as to which track to look at.

Hope this is at least some help until the Empeg guys are here again.

BTW beaker - please break your text into paragraphs - it's hard to read in the stream-of-consciousness style...