Hmm interesting. I do have the auto-play on (if by that you mean it starts playing where it left off) - but I still have the auto-shutoff set for 8mins, so no matter what it should never be left on for 8 mins, right? Maybe there is a bug where I am somehow not allowing the auto-shutoff to turn the x5 off, and the auto-play is just running it all night long? I would guess it's either that or something weird with the battery itself, but this only happened twice I think.
I don't find that the X5 goes to normal mode when disconnecting the power supply as my unit is turned off before charging. When I disconnect the power supply my unit has to be turned on
I can understand this behaviour if the charging is started while the X5 is switched on and playing.
after extensive testing it seems that you are correct, if the player was off before charging, it shouldn't do this.
my guess is a broken battery. contact firstname.lastname@example.org :)