I buy these lights not working all the time. 90% of the time the switch is bad. If it isnt the switch i try a starter off a light i know works. Then i try bulbs i know work. Leaving the good starter in. Then I clean all connections. Then i replace the endcaps. Then I replace ballast. If it gets to point where all things I know are good like bulbs, starter, switch and connections are all clean sometimes I just scrap it. I can usually get these for $2-3 in not working condition.