I have the same issue. My galaxy keeps resetting. Its done it so many times. I have done factory reset about 5 times now. As well as formatted everything about 4 times.Its seems fine for a couple of days, then resets again. The only apps I reinstall are cainer and colour note. I also change the font to a paid one. I have taken battery out and left it in sun for half hour, also ive taken micro sd out. But still it resets. I am in second year of contract, so im stuck. I really like the phone, but constant resets are frustrating.
I have just purchased new battery online, and Im hoping it just a battery issue. Any help would be greatly appreciated.