Rockbox

Running Rockbox release v2.5, not flashed, on a Jukebox
Studio 20.

I had resume on, and shutdown using the Stop button, as
is my normal practice. I transferred some new files,
(via USB), and also renamed a number of files,
including the song which had been playing when I shut
down (yes, it was a dumb thing to do). When I turned
the player back on, I did not see the normal startup
screens (no "Jukebox ver: 5.06", no "Rockbox"). The
song which was playing last did resume playing, but
there was no title displayed (the battery, volume,
Play icon, and "Audio" icon were displayed). I could
stop the tune currently playing, but had no other
controls. Menu would display a "Param" icon but had no
other effect, On would cause the current track to play
if it was stopped, Play would cause the current track
to play if it was stopped, Stop would stop the current
track if playing, or turn off the player if held down,
+ and - had no effect.

I powered the player up and down several times, and
eventually reinstalled Rockbox to solve the issue.

Details:
Jukebox Studio 20 flashed with Jukebox v 5.06, running
Rockbox v2.5
From debug menu(HW Info):
Rom 5.03
USB: neg
ATA: 0x300m
Mask: 0000
Flash:BF,D6
RomCRC:222F