Default [Q] Power button issues

Gentleman, my optimus g is showing some really strange behavior. If the battery is fully charged, or above 60%, it works flawless, after it drops below that, there is a chance that the power button will start locking in the pressed down position. After this happens, it is a no come back, the phone keeps bootlooping until the battery goes dry. At first I thought this was a problem with the battery, I got It replaced and the problem persists. I am starting to think this is a problem with the power button flex cable, and I was wandering if anyone knows how to replace it. I've replaced cell phone's screens and such, I have taken the motherboard out and found the flex cable, but I am not sure how to remove it, as it seems that it is firmly glued to the chassis. If anyone could give me some suggestions I would appreciate it, thanks