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Without a model number I can only really guess, but I do think I know what is wrong with your set, there were a bunch of models around the time you bought yours that had this problem. If yours is the model I think it is then this is actually a common problem in your model and is well known for doing this. What has happened most likely is your Y or Z sustain board has failed and needs to be replaced, both of these are about the same price to have replaced as well. The average cost of replacement for these is $550+ tax, the repair price, however can vary depending on the part of the country you live in and the shop you call out. Sometimes smaller shops that are less dependable will charge less than the large outfits with big overhead costs. If you have electronic repair experience, and test equipment let me know and we can troubleshoot this together, however if you do not a repairman will be required. These sets are fragile and you MUST know what you are doing when repairing them or damage can be caused to them, or you!
This is an unfortunate problem because these televisions should last a lot longer than they do, however the age of them doesn't seem to affect this problem at all. We do warranty work for most of the major manufactures and I cannot tell you how many 1 week old televisions we have done major repairs on. Also the same problem that might have happened to one person's television at 1 week old might have happened to someone else's at 3 years old. These new sets are a shame to be honest with you, nothing is made the way they used to, or the way they should be for that matter. The average span of time for a new plasma or LCD television to last before its first major problem seems to be anywhere less than 3 years.
I am sorry that I do not have a quick fix or easy answer for you on this one, but this set will require board replacement in order to get it running again. Please let me know if there is anything else I can do for you, I will be happy to assist in any way possible.
If you would like any additional information or have more questions please don't hesitate to ask!
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