How to troubleshoot a florescent light.
Yes if they don't light and the ends of the bulbs are black you just found 1 answer the bulb is bad. If you replace the bulb and still have trouble your problem is the ballast, electronic ballast die when overloaded. I almost left a sarcastic note at the end of this but will explain. After just changing 3 ballast in very high end fixtures that the owner was two cheap to change lamps. The cost of new fixtures almost 700.00 plus install. I purchased 3 cheap fixtures and pulled the ballast cost just under 110. For the same ballast. I made 400.00 to replace them. Not bad for a few hours work, If he changed the lamps would have cost less than 35 at Home Depot