iPhone 5 won't turn on after opening

So I opened my iPhone 5 because I wanted to do a battery replacement. First time opening it went compeletely smooth but for some reason the connector of the new battery didn't fit into the slot. Only the left (or bottom) side of the connector seems to fit. Then I decided to switch back the old battery and reassemble the phone just to see if it still works, and it did. After that I realized that I didn't put the shield that protects the ribbon cables coming from the screen back on.

Next time I opened the phone, I pulled too hard and the whole screen came off with the ribbon cables. Now the screen stays black when I try to power up the phone. So did I ruin the ribbon cables even though there is no visible damage in them? Is there any way to be sure if the ribbon cables are the problem?

Thanks