if your power button is unresponsive it may have become unseated in its housing. To fix this please place two fingers on the volume button and gently rotate them in a circular motion. If you feel the button shift and then lock into place try and see if the button works. If the button does not work after this you may have either a broken or faulty power button. This could mean either the power button cap or the physical switch on the motherboard is broken. Please follow this link to troubleshoot and fix this problem: Alldaymall A88X Troubleshooting.