REPAIR Question--Genesis Model 1 Reset Button; Possible Short?

[HeadcolorsTV]

My client's Genesis powers on but with no video or audio. Cartridge pins have been cleaned, retensioned and tested for continuity. Clock signals are present and steady. The RGB encoder tests good with the correct voltages at all inputs and outputs. I wondered if the system was in a constant state of reset, as the WRES pin of 315-5433 (IC4) showed 5V when probed with VDD (but oddly didn't test continuous with ground).

 

I first popped off the rubber piece and tested the open connectors with the power on: continuity. It's acting closed. I removed the switch component altogether and tested the thru holes, again with power on; here's where it gets weird:

 

• the two holes in 5V rail have continuity
• the two GND holes have continuity
• testing GND with the negative probe & 5V rail with positive probe: OPEN; no continuity
• testing GND with the positive probe & 5V rail with the negative? BEEEEEP. It's closed!?

 

See pics. Same goes if I probe the two open pads where C80 is labeled (left open in factory). Beep. The two diodes next to the switch also test perfectly fine (0.8V each).

 

Is this supposed to be the case? I find it really weird that the voltage for the switch is shorted to ground, but *only one way*.

 

Now I do notice--it's hard to see in the pics--a tiny "speed bump" in the thin void between GND and 5V trace on the left side (see 1st two pics). Is that where the short might be? I'm thinking about scratching that little part of the void to sever any possible short, but not until I get a second opinion/more enlightened on how this circuit is working.

Edited 8 hours ago by HeadcolorsTV
Corrected typos