Blinks 7 times then stops then starts blinking again.

I have the same issue (7 blinks, black screen) TH-42PX60U. It used to happen intermittently but start working again after being unplugged for a bit or powered from another wall outlet. Eventually, it became permanent. I have got a new TV but don't want to junk it. So, I opened the back and tried troubleshooting as indicated on several related posts on ifixit. Checking the connectors and hard reset didn't resolve the issue. Disconnecting SD and SU boards (how is this done? I alternatively disconnected the dozen wide orange ribbons on the left or the two different types of connectors each between SD/SU and the SC board. That did not resolve the 7 blink. Disconnecting the three connectors on the right of SC board (coming from SS or other boards on the right and not from SU or SD) did stop the blinking and the light becomes solid. The SS board LED light also remains solid at this point.

All indications are it is the SC board (and possibly SU/SD). Disconnecting just the SC 20 connector stops the blinking (and SS led turns solid green), but disconnecting only SU and SD from SC by and doesn't stop the blinking. I have looked closely at the SC board and cannot find any signs of a damaged part. A resistance check (multimeter grounded at floating screw and at any position on the pins of the connectors (between the SC board and SU/SD boards) suggest a short circuit). Should I just go ahead and get a replacement SC board or is there a way to check and repair the SC board? I can do rudimentary soldering. The board is $30, the TV is $60 probably at this point. Still, a working TV is less electronic waste.