The Z250i phone turns itself off
Restart the phone or do a master reset.
To restart the Sony Ericsson Z250 phone
1. Turn the phone off and remove the battery cover.
2. Remove the battery and put it back in place.
3. Replace the battery cover and turn the phone on.
To perform a Sony Ericsson Z250 master reset
1. From standby select Menu > Settings > General > Master reset.
2. Select Reset settings to delete your changes to settings or Reset all to delete your changes to settings. all contacts, messages, personal data, and content you have downloaded, received or edited.
3. Select Continue.
If nothing works: As last resort do a Sony Ericsson phone repaire with PC Suite. Use this method to hard reset AFTER INSTALLATION----> TOOLS > PHONE REPAIR