sound but no pic on hitachi plasma tv

I purchased a 42" hitachi plasma tv (model 42edt41) in November 2004. 3 wks ago I turned the tv on to discover there was sound but no picture. (of course, the manufacturer warranty has expired & the retailer of purchased it from closed the store so the extended warranty i purchased-at least to the best of my knowledge-is no good. I did the suggested troubleshooting methods from the owner's manual (check how power cable is connected, press power switch, check signal cable) however I was unable to check the contrast & brightness setting since this can only be done via the menu. (no pic to view menu) called Hitachi's 800 number to seek assistance, the only other suggested the help desk offered was to unplug the tv for 5 seconds then plug it back in & turn it on-still no pic. The tech said since I had no pic (menu can't be seen) there was nothing else he could do to help other than to call a qualified repair person since neither of the warranties were good. (by the way the Hitachi website still lists & the help desk still offers the store which I purchased the tv from-which closed in March 2005-as 1 of the locations where service for this model is available) I made some calls to try to obtain some help to firgure out what may be wrong & didn't get any. (other than finding out the cost to have a repair person come to my home & "look" at the tv-I received no promise that it could be fixed- was not cheap-$150 1st hour was the lower price. I located another location for the retailer I purchased the tv from-1 hr away from me-however they won't send a repair person here b/c extended warranty wasn't purchased thru them (I explained it was the same store name) but manager I spoke to only offered bringing the tv to the store to have it looked at. Can anyone suggest what else to do or offer an answer to what is wrong w/ my tv & how to have it fixed?