Phone won't display after wifi antenna flex cable replacement.

Hello,

I have recently replaced the wifi antenna flex cable (the f-shaped cable). When I went to reconnect the battery toward the end of the repair, I was unable to get anything but a black screen. I put the old wifi antenna flex cable back in (because it previously worked, albeit weak wifi and terrible GPS), and still nothing. When I plug the phone into the computer, it recognizes it as my iPhone, yet when I search for it using "Find my iPhone" over the PC, it shows that it is offline. I know that it turn on and off because my car also recognizes it via USB (of course I turned off Bluetooth right before the phone stopped working, so I can't test that). Has anyone else had this issue? Any input would help - thanks!