True, it could be the battery. Still, I'd take the battery out for a few minutes to let the phone reset, then put the battery back in, don't try to power on yet, plug the phone into the charger, wait 5 minutes, then try to power on the phone while it's still plugged into the charger. If it won't power on while it's on charge, it probably is not the battery, that's when I'd start to wonder about the phone.

My guess would be that the battery is crap. Maybe try getting a new one.
good luck with it.

I just bought a samsung sgh E635 off of ebay and it seemed to work fine the first day but this morning it was turned off when I got up and it wouldn't power on. The screen will briefly flash on and then off. After a 30 seconds to a minute it will flash back on and then back off, over and over again.

I thought maybe it had run out of charge during the night even though it had a couple of notches of battery when I went to bed so I plugged it into the charger for an hour or so but it's still doing the same thing.

Does anyone have any idea what's going on with it? I guess I'd better contact the seller and let them know it's damaged.