Not sure if we're making any progress here. So you took the SS out of the equation and it gave code 7.
This is the error code for the SC (& SU or SD) but you say you've tested the SC using a shorting link on SC50. Did you lift SU and SD completely away from the SC - no need ( and not wise) to remove the flexies that go to the panel from SU/SD?
If you remove connector SC2 and reconnect all else, does it still give code 10. IF no, then I'd blame the SC. If it still gives code 10, then unplug A11 and power the tv on. If code 10 persists, I'd say A board faulty, otherwise the P board. Bruce