Help S2 randomly turns off after splash screen or lock screen

[alex_ncfc]

Hi, hoping someone can help.

My girlfriend's S2 phone has been fine until yesterday when she said it was very hot. Now it doesn't stay on. When starting the phone on battery power, all of the start up screens function normally, but then it will power straight off after the last splash screen.

If it's on charge via USB connected to the laptop, I am able to start the phone but this time it goes further and will stay on the lock screen - if I keep pressing the home button when the screen goes to sleep, I can again see the lock screen. As soon as I unlock the screen, the phone goes to the home screen but then powers off instantly.

I have started the phone in the recovery menu modes, on battery, and it doesn't turn off then. Is there any way I can get the files transferred from the phone to the laptop? I connect the USB and Kies starts to find the phone, but I am having a hard time getting the "MTP USB connection" screen, or whatever it says, to come up.

What could be wrong here?

Thanks

 

[alex_ncfc]

Just noticed that it's when the battery gets to 100% charge (it vibrates) that the phone disconnects from the PC. Does this phone by any chance stop charging at 100% and go to using the battery? Seems to be the battery having no juice but it always seems to be on or near 100%. If there was some way I could drain it then maybe I could have it connected to the PC long enough to do a backup in Kies.