Bad Proximity sensor or bad Mobo? Help
so i recently bought a broken iphone for my friend because he wanted me to replace the screen for him. i replaced the screen and unlocked it using blackra1n and when i make a call i cant hear from the earpiece and the screen doesnt go blank when i bring it up to my face. i tried to figure out the problem and i used my iPhones top part (digitizer/lcd/chassis with all components) and plugged everything correctly into iPhone A(friend's iPhone). so now iPhone A has the original motherboard, but it has my (iPhone B) digitizer/lcd and the components that are attached to it(earpiece, home button). i tried to make a call from that phone and now the earpiece works but the proximity sensor doesnt work. i know for a fact that the proximity sensor works since it was on my original iPhone and it worked fine while on there. but it wont work on my friends iPhone.
Do you guys think it is a bad Mobo? or is it something else?
thanks a lot