Just thought I'd post a success story and thank the site. There's a lot of good info to glean from here. Anyhow, my tv had the 7 blinks, I used the 2011 troubleshooting guide found here, and determined it was the sc board. I wasn't comfortable attempting the fix myself since I have no soldering or diagnostics experience, so I sent all three boards (sc, su, and sd board) to a repair service on ebay. Two of the boards were damaged, so I'm glad I didn't try to fix it myself as I would have only worked on the sc board based on the troubleshooting guide. I've got my plasma back and hope the fix lasts several years -- I love this tv and it's picture. Thanks to all the knowledgeable members!
It's a tc-p55gt30
It's a tc-p55gt30