z3c won't turn on. Flashes battery charging screen when plugged in to the wall.

I just replaced the cracked screen on my z3 compact but the phone won't turn on, and when I plug it in to charge, it flashes the battery icon. When I plug it into my pc, windows makes a noise, but won't recognize the phone.

I followed a guide from ifixit and an accompanying youtube video.

Neither of them removed the battery before changing the screen connector, but people were telling me that may have fired the phone?

Is it for sure bricked?