Hi!
it can be a Rockbox issue, and little help to me.
OK. Let me explain. Few days ago I clean up (physically) my Sansa e260 and the battery became a little bit fat. I don't want to buy not original battery to player, so I thought "So maybe I can tranform my portable player into stationary tool that can monitor CPU Usage, HDD Usage, maybe I can control the cooling fans inside PC, maybe even display some infos directly from the games, like Logitech G15 keyboard! Or even more! Maybe sky is the limit!". So yeah, I've done very small, let's say "research" and check if Sansa can start without battery. And the answer is "Yes, but not on the Rockbox". Original firmware starts when just plug USB to player, and it becomes "Connected". On the Rockbox situation is a bit different, because it starts, but after few seconds "Shutting down" is visible, then restart and so on, but! When I plugged USB cable with battery and when Rockbox starts to "USB Keypad Mode: Multimedia", then you can remove battery and Rockbox still works (you can play/pause, click Next/Previous, control the volume). Unfortunately after PC restart, whole procedure with battery need to be done.
Soooo, what do you think?