Power button not responding

A

AC Question

Recently I started flashing ROM's in my Alcatel POP 3 (5) running 5.0.2 Lollipop.
I flashed Cyanogenmod 12.1 which works pretty well, better than stock actually to be honest.
But then I decided to go back to the stock ROM and that was when it all started. My power button started not responding sometimes but if I clicked the volume buttons a few times it would start responding again after a while so I thought it shouldn't be a hardware problem.
The CM ROM got updated and I flashed it again with TWRP 3.0.0.0 and the problem still persists but got worse.
Now my power button only works when I let my phone completely reach 0% and still gets glitchy while its discharged and is difficult to boot up the phone. I already tried to boot through adb reboot and fastboot reboot but my win10 x64 doesn't recognize my device, and whenever I go to fastboot mode I have to let the phone totally discharge to be able to charge it again and then turn it on, such pain in the a** cuz I have to wait about 8 hours to be able to use my phone again!!
So I did some research and found out that I should open my phone and remove my non removable battery, I tried that method and started to open my phone back to get access to the motherboard, battery...
But the back wasn't coming out easily and I was afraid of removing the motherboard or damaging it by mistake and then there would not be a turn around to it.
Can anyone tell me a way to fix this without removing the battery?