Why is my iPod 5 rear camera screen black?

I cracked it a while ago, but both cameras (front and back) still worked.
And then I tried fixing it myself with a new screen, but i pressed too hard on the screen which messed it up, but both cameras still worked.
So then i took it some place to get it fixed, which i payed a lot for, and he fixed the screen but then when I tried to use the camera it was black.
My mom took it back and he said he wanted my password for it, but i wasn't there so i wasn't gonna just give it to him. He said he needed to look in the settings or whatever. But i wasn't there so i wasn't gonna hand out my password over phone. So i just took it back and looked at all the settings and nothing would change anything.
I tried restarting a couple times and i reset it. When i reboot it sometimes the front camera works but the back doesn't. Its either just black or it freezes.

I just updated to iOS 7.1.2 so maybe its a software glitch? And my flashlight doesn't work either.
If i can't get this figured I'm gonna be really mad because Apple products keep messing up so please help.

Im not paying anymore money trying to fix this after so many times. If there are any free camera apps just like the normal one could you please tell me. Im honestly just done with apple products. They all break after like 2 years.

P.S. I have no case on it so the case isn't blocking it or anything.