[Q] Bootloop and power button not working HELP!! topic

I was running unoffcial cm12 for my desire 816 a5dwg variant. My power button just got stuck inside and doesnt work so I had to send it for warranty and so I planned on making my desire 816 stock again. I used the windroid universal kit and relocked the bootloader using it and after that my phone is stuck in a bootloop and it boots to the hboot. I've tried pressing volume keys but before I do anything it switches off. It runs only for 20 seconds and then reboots again. I need to get the phone to stock as to make a claim for warranty. I know there are so many talented devs out there who would have superior knowledge and can help me fix this. Please help me. Thank you so much in advance :)