If the service technician can't or won't replace the board, you might call back 800-SAMSUNG to see about having the unit re-repaired or what other options you may have. I'm sure if you explain the situation, you'll likely get favorable results. Unfortunately, only service can address service issues, and I can't assist with that here.
I've got a UN40C6500, when I recieved this TV it had horizontal green lines on all input sources, we had a mainboard replaced it went away, I flashed the firmware, it restarted without video, a new mainboard was installed and I'm back to having horizontal green lines again, now Samsung tech recomends that the TV repair technichian not replace the mainboard because they state that no 2 boards can have the same problem. What can I do to get the TV fixed before going to Samsung Executive customer care???