Identifying whether display is broken or the motherboard

I assume it is possible to damage the motherboard / chips inside a phone if it falls on the ground. So my questions is, is it possible to confirm what has been damaged during the fall? I don't want to end up buying a replacement display and then found out the problem is somewhere else. The phone is JiaYu G3T (a Chinese brand), fell on a ground. I completely disassembled the the phone but I didn't find any damage anywhere, everything looks like new. Pic 1. This should be black with a green logo, left part of the screen is darker than right Pic 2. Again, half of the screen is darker, color problems at the bottom OR sometimes the same as the startup screen - grayscale-kind-of-inverted-colors display