I don't now anything about the X30 but the X51V does have a small capacitor inside that will go bad. The purpose of this capacitor is to keep the date & time while replacing the battery. I don't know if your date & time reverted back when you took your battery out.
I did a Google search & found some stuff you.
Problems with Dell Axim X30 Pocket PC
Backup battery - Axim Users Dot Com
Replacing X30 backup battery?