First try a complete factory-reset!
If the writable memory is corrupted (logical errors) a complete reset (factory reset) could help.
"
Factory reset" is often named "
hard reset". It's not just using the pinhole on the reader. In my case "factory reset" solved various problems.
It's for the 650, but same for the 350. Factory reset:
http://www.factory-reset.com/wiki/PRS-650
PRS+ and warranty:
I sent in 2 different PRS350 on warranty with PRS+ on the reader und that fact wasn't even mentioned by the repair center. Warranty repair without charge both times.
A.