Q & A automatic restart after shutting down device topic

Hi. Im currently on prerooted 5.0 without xzdr with unlocked bootloader. I cannot completely shutdown my phone. once it's turned off, it turns on again by itself. It's really annoying as it will stuck in bootloop with the sony logo. I have to force shutdown the phone to turn it off completely. It can be turned on normally after a force shutdown without a bootloop. When it boots normally, the green led light is shown. Could anyone give me some guidelines in fixing this? i have tried to flash back to stock 4.4. then root. xzdr. then upgrade to preroot 5.0 . it would be appreciated if there are some ways to solve this. thank you so much in advance.