In the last year, my friend and I have had MULTIPLE failures of the coralife t5no fixtures, both in 30" and 36" lengths. Changing bulbs does nothing. In every case, when you flip the switch, the light will briefly flicker (so brief you wouldn't see if you weren't closely watching) the it goes dark. Between that and the abysmal PAR readings we got off of them, we both finally gave up on them and got different lights. Sorry you're having issues, but it definitely seems to be a widespread problem with this brand.