+18 Built In Led Ceiling Lights Wont Turn On References. Web the first thing you should do is check if the ceiling fan is plugged in. Identify the problem step 2:

Open the bottom unit and look for the “hot”. If it's not, then plug it in and see if that solves the problem. Web to check for an led light that is not working, 1st make sure that all the leds are connected properly.