My 34UC87C led me here.
though it’s a different monitor the jumping worked here’s what I did.
I jumped pins 8 and 6 without luck. Then I wondered how the fix works.
If the rom is on a loop maybe screwing with the clock causes an error or jump elsewhere.
So I rapidly shorted 8 and 6 a bunch of times. It eventually worked.
pin 8 is vcc so safer than that post about an ammeter.