T5 HO repair question

Looking at the picrures but not seeing the bulb holder leaves room for error but it looks to me like the red wire may have gotten a bare part touching the bare metal. The yellow wire and the holder may have been innocent by standers who got burned in the flash. I might have expected more burning on the metal also, so it may have been the holder which failed. In either case, It should be somewhat simple to replace the holder. I would suggest for peace of mind, that I would slide a tube of heat shrink over the burned yellow wire. Once burned the insulation often tends to get brittle and then crack off at some point in the future. That could wind up giving you the same trouble again later. Better to protect it a bit now while handy.
The ballast needs some more info. Does it have one or two ballast? If two, you can test by swapping the suspect one with the good one. Ballasts can be arranged several different ways so it is hard to say at this point.
That bare metal sure would have been a good place for them to add some quality by putting just a dimes worth of tape over the raw edge!!!