iPhone 6 screen freezes, glitches, then restarts over and over

Hello.

I’ve found myself to be having problems with my iPhone 6 screen after a touch display replacement.

When I’m using apps or browsing through Safari, the iPhone seems to overheat, the screen freezes and then glitches, just to turn off and on again, and repeating the same glitching process. The glitch turns the screen into a lot of colors like green, blue or purple. To fix it and keep using my phone I have to wait until the phone turns completely off, and then I make a hard reset.

I’ve already restarted all settings, hard reseted it lots of times and restarted my phone from scratch, but it doesn’t seem to fix.

This bug is really exhausting and I’m wondering if it’s a software problem, a hardware one, and how to fix it.

thanks!