To add fo the confusion - I think I see this here at work, in a docking sled with a dummy plug to put the player in AC mode. So I don't think it's a car-only issue.

It's fine at bootup, but if I put the unit into standby, then wake it again, the display doesn't appear for 2-3 seconds, then it appears with the battery icon for another 7-8 seconds.

No messages appear on the serial.

Like you, I have yellow and orange both tied to +12V and black to 0V. Amp control output, and the mute and lights inputs are all unconnected. Audio out and serial are through the docking connector, Ethernet via the socket.

Hijack v288.

Anything else you want to know?