I bought an used Iphone 3G currently on 4.2.1 factory unlocked. It worked well for around 10-15 days. Thereafter it started getting switched off randomly when in pocket or placed elsewhere even with almost fully charged battery. It wont restart even after connecting to the charger. When connected to Itunes, It detects Iphone in recovery mode and asks to restore it. But if you dont connect it to Itunes and leave it in same switched off condition for a day or 2, and then try to charge, It starts getting charged with battery totally drained off. I know its not a battery issue since sometimes it works realy great and the battery charge lasts for a full day which is decent enuff with my Usage. I tried searching a lot but never across such a problem. Would be great if someone can help me out with this