Can you share it online for others to read what to do next?
Often we fix such by changing boards. Since the boards run a few hundred most non-TV repair shops cringe at the fact we may have to change 2 boards.
I've got a TH-P54S10A Panasonic Plasma and when I turn it on I get the 7 flashes of red. I've found mixed comment on this issue but not directly with this model. I've opened the back and ready to fix the issue... any suggestions?