I can't power up my Gigabeat.

[deehunter]

*Update*
Switching the battery switch off then on caused it to power on properly. Sorry for the disturbance!

On Monday night, as I turned my Gigabeat F40 off, I got an error message:

*PANIC*
Event Not Found

I hit the power button again and my device did shut off, but now I can't turn it on.  Its remaining battery power was over 90%, and it can still be charged, so I know that's not the problem.  Its Rockbox revision number is 17111-080415.