iPhone 5 backlight problem

Hi guys,

a customer brought for us an iPhone 5 for service. He said the phone was fall down, and the lcd display is not fitting in frame, and the backlight was gone. I opened the phone, and I saw with microscope, but I didn't see any problems in the logic board (etc. connectors, coils, filters). I tried different lcd , but the screen doesn't well as done. After 2 days, I tried turn on the phone, and worked very well, but after 5 hours later, the backlight was gone.

what is the solution?

backlight ic?

thanks