Hi, if it's not the battery it's either the EROM or the GDFS which are both parts of your software..
If the phone is fully charged go onto the SE website & find the updater for restoring or upgrading your software, select your phone & the software will do the rest.
You will need your data cable (DCU-60) then just hold the C button when connecting, it tells you this on the site anyway.
GATORS
May 2009