Not a power board. 7 blinks is SC, SD or SU, and the SD/SU can be eliminated with a little jumper on pin block SC50. SU and SD total won't set you back more than $100, if they're not rare parts.
Panasonic are REALLY nice to repair. They rarely go wrong (boo, less experience and easy fixes for me like Samsung) but they have a very nice diagnostics feature which essentially tells you exactly where the problem is, even down to the circuit level.