After screen replacement the screen turns on by itself when locked

I have replaced the screen and soldered the old sleep/wake sensor onto it. When the ipad is not plugged in, it refuses to keep the screen turned off. If I hit the power button, the screen turns off then turns back on after 5 seconds. If I leave it, the screen turns off after a few seconds, and then turns back on after a few seconds. It repeats this process of automatically turning the screen on and off until the battery dies.

Any ideas what could be the cause? The ipad was dropped on the corner where the power button is found, but prior to the screen repair did not have this issue. I’m pretty sure the soldered sleep/wake sensor is working because I can lock it with a magnetic cover (though even when locked with the magnet cover it still wakes 5 seconds later and goes into the cycle described above. This behavior also occurred when the sleep/wake sensor was not attached.

This behaviour does not seem to occur if the ipad is plugged in.