iPhone 3G reboots after being "locked" for longer than 1 minute

Hi guys,

Got a weird one here.
I have an 16Gb iPhone 3G (running iOS 4.2.1) and recently replaced the LC screen as it was cracked.

The screen now works fine, so too the touch screen and all buttons.
However, if I lock the iPhone (top button) and wait about 1 minute, then try to unlock (either by round button or top button) it hard reboots and displays the apple icon.
It will continue to do this until I manage to unlock successfully, by timing it and unlocking just after the iPhone has reboot fully.

Once unlocked, it is fine. Everything works.
Pressing the top button to lock again, no worries. I can unlock without a problem, as long as it is less than a minute...

I've tried a full restore (via iTunes) and the problem persists.

Any ideas?

Cheers

edit: Just been playing with the lock/unlock sequence, now a white screen is displayed every 5 or locks, not the black screen... iPhone still unlocks without an issue.
Just left it sitting there, locked, tried to unlock after 1 minute, and apple logo and restarting...

edit 2: Having wifi, network off, and even aeroplane mode on, does nothing

edit 3: Got it (I think).
Having the iPhone plugged in and charging seems to work. I can lock and wait over 10mins, then unlock without a problem
I guessing this is the battery then. Will replace with a new one and get back with the results...

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Last edited by maccacino; Today at 01:03 AM.

Source: http://forums.macrumors.com/showthread.php?t=1295318&goto=newpost

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