Hey I got one of those phones and I have seen some square colors bars on the screen that flashes when I'm using games, those bars comes from the upped left part of the screen to the middle of the screen, it just flash for a second and get more frecuent when using more you intensive games like PSP emulators, it happens with Pokemon go, ppsspp, peace, AnTuTu bench, Möbius final fantasy, and sometimes while watching YouTube. On other website people say that is something about software and happens with the build b08 which I have, I you have the same or a solution please let me know. By the way, I've tried the "disable hardware overlay" on developer menu (it only makes the menu and scrolling a little slower (maybe BC the GPU is slow) but doesn't fix it.