restarts when ever it wants to.

Finally broke down and started dismantling mine (see screen replacement instructions). The metal shield around the battery compartment just below the camera is sharp and chafed through and shorted the flex cable to the shield. If this hasn't destroyed the power supply your phone may be recoverable. If you see this use thin quality tape to cover the short, reassemble, and test. If it works bending/trimming the shield may be a more permanent fix.

once I had a bad battery, that made the phone restart when the phone needed some power(for example when started downloading something, turned the wifi on, turned the flashlight on, used bluetooth, etc) that was because the battery was not powerful enough to deliver the current to the phone and it caused reboots, after a while it caused the emmc of the phone to fail and it actually killed the phone. :(