Backlight of my Kobo Clara BW is not working

Kobo Clara BW backlight stopped working after it ran out of battery. It gets glitchy and backlight does not respond when I try to turn it back on. I tried factory reset and updates but nothing works. Glitch is also a bit strange, it's like the frame rate is much slower or commands take longer time to register. Is the problem with screen or motherboard, can someone help?