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I replaced the battery in my 3GS using the tutorial and everything seemed to go smoothly. After putting everything back together the iPhone booted up and acted correctly. However, it reboots every couple minutes. Any ideas? Thanks!! UPDATE: It appears the battery is defective. I reinstalled the original battery and the problem no longer occurs.

Original Poster’s Own Answer It appears the battery is defective. I reinstalled the original battery and the problem no longer occurs.

I had the same exact problem, turns out, I had a OEM battery for the 3g. Got the correct one, everything worked great.