Reinstall the screen with the front camera detached and see if that kicks it out of the loop. The cameras are very fragile and often times when the phone gets hot, It damages the camera and causes that to enter boot loop. If this works, simply replacing the front camera will usually fix the issue.
She just ordered the glass, Spend the extra $15 and buy the LCD with it also. You will end up breaking the LCD on the old screen trying to replace the glass only. It will be way easier to replace the whole assembly, than trying to replace just the glass. It will also be way faster.
Were the cameras working before the screen replacement? If the LCD was broken and you weren't able to check them, its possible the cameras were damaged on the motherboard at the same time the screen was broken.
Is the mesh on the actual screen plugged with dirt or dust? That’s usually the most common issue I come across. Either replace the screen, or if you have old screens laying around replace the mesh that is inside. Obviously option 2 is cheaper.