Iphone 5c no display – iphone problem , and strang hardware strange problem

I have one iphone 5c Along with no display, no backlight. Its not a water damage. Customer give to me Along with no display for change screen. I change but same problem (lcd is ok on another 5c), i test many screen. I restore many times but same. In recovery mode, i see the logo. When i restore, no display on iphone 5c, restore and activation is ok. I restore on two pc (only motherboard, battery, and connector) but same. I wait one week Along with motherboard only and restore done, same problem.

I think its hardware problem, have you got solution kindly or schematic.

Thanks in advance.