guys, you rules !
Indeed, I powered them off just by unplugging the cord before servicing ...
The test mode with AMS + STOP worked fine. Display on, all button working but unfortunatly the repeat button did not work.
I did check the ribbon cable a million time even before posting this thread. No better luck.
However ! I remembered showing to my kids how the motor was turning and moving the laser head from right to left .... Moving the head back in park position simply solved the problem on both drives ...
Two conclusions :
- NGY was right.
- Never works with your kids arround
Thanks you all for this success.