[Q] screen flicker during boot xt1033 topic

Guys im using xt1033 i converted it to gpe 4.4.4 and tried updating it to 5.0.1 via otg sideload and i got stuck in Google unlocked logo and so that i flashed stock rom again.after that whenever i boot my phone or whenever im in recovery there is a line orginating from top and flows till the bottom continuously. This stops only when i turn off the screen after boot and turn it on. Then my phone works normally. I wanted to know that weather this is a problem due to flashing? Or due to hardware? Or something else ? Need solution for getting rid of this. I also wanted to know that weather i can flash roms with this problem ? Im scared that my phone will not work if i flash something with this problem. Guys please get me through this... Thanks in advance...