Help Please! 35 days from flip. At lights on my 600w HPS light ( about 4 months old) burned a bit and went out. I replaced the bulb but nothing. Touched the cord and it came on for a few minutes and went back out. I was thinking short because it will pop on intermittently and go back out a min later. If I unplug the ballast, wait a few mins and turn back on it lights right up but then shuts off again after a few mins. Is this a sign of a bad ballast??? arghhhhh