Sony ES 5046 issue

I bought this amp on a whim about a year ago and it was an OK sounding unit. I ran it over the summer, letting 2 channels power some piezo tweeters, and other 2 channels powering doors.

Unit had been on at normal listening levels for roughly 25 minutes, shut car off, and roughly 2 hours later when leaving, turned HU on and immediately noticed an issue. It's not completely dead, but produces a low-output garble on just the one channel. At first, thought the tweeter was cooked as that's what it sounded like- like a cooked voice coil in a normal speaker. I verified the tweeters were actually OK, and the other 2 channels were working as they were supposed to.

I know it's not much to go off of, but does this sound like a failed output? Or could it be something simpler like a failed cap? A visual revealed nothing burnt or obvious. Unit has been collecting dust and would like to get it working again as it's too nice of an amplifier to let it fall victim to a trashbag homicide :(