RCA t09085 and other t##### models service menu!
Edit: Set VOL to 0 first.
Press VOL - (on the TV) and 9 (on the remote) simultaneously to open the service menu.
CH to switch items and VOL to change values.
Posting here because after days of searching and close to 40 useless PDF downloads I finally discovered the service menu combo for my 9" RCA TV by accident, hopefully this helps someone who was lost like I was.
