next time it wont start, pull the yellow wire off of the "ign" terminal to disable the starter & have a helper hold the key to "crank" & you with your meter or a test light see if the coil positive primary terminal & the blue/yellow ECU terminal are being fed & work upstream from them to find the open. In the meantime as said I would clean/wiggle all pertinent connections/terminals starting with the ballast & pull & put back in place the bulkhead which alot of times is enough to restore continuity there. short version: if all you touched/wiggled is the ballast then as said check its terminal connections & replace it. EDIT In fact what I think I would do is bypass it & see if it will start a half dozen times right in a row & dont let it run more than several seconds each time.