Camera light and both front and rear camera won't work.

I installed a new iphone 6 LCD screen and digitizer assy. for my daughter. Everything went great and was working fine. After she received it, her only complaint was the speaker she puts up to her ear sounded terrible. I swapped the speaker out for the one that was on her old cracked screen and it sounded great. She loved the new screen and the way it sounds. But, after changing the speaker out she says neither camera (front or rear) works or the light works. She said the light won't turn on and both camera's just have a black screen. She is 20 and in college. I have been changing screens out for her starting with the iphone 3 and just about every model since and never had a problem. Can somebody give me a suggestion to try before I have to buy her a new phone please.