My Mitsubishi WS 55511 died.
If you are lucky, it's only a blown fuse. Some tv's this large have more than one fuse, so look real hard and find all fuses. If fuses are good, then about 95% of the time, when you have no picture/no sound, the problem is a bad H.O.T. This is a large transistor with three pins soldered into the main board and is very easy to find because it is connected to a metal "heat sink". Look for a large red or black wire coming from the pic tube down to the main circuit board (sometimes it's blue, but it's the only wire coming from the GLASS part of the tube to the board. This wire goes to about the largest component on the board called the "flyback transformer". It is usually black and is about 3 or 4 inches tall, 2 inches wide, and 2 inches thick. The h.o.t. will usually be located in the area of the "flyback". The h.o.t. will be screwed with one screw or clamped onto a large piece of metal (usually silver). This piece of metal is usually about 2 inces square and is about 1/8 of an inch thick and is mounted perpendicular to the main board. Imagine a slice of bread standing on one side rather than lying flat and this is what the heat sink looks like. Sometimes you will see several heat sinks with transistors screwed into them, but the one you are looking for will always be the largest transistor with three pins. Don't forget to unplug the tv before you begin and stay away from the large wire coming out of the tube going to the "flyback". Do NOT unplug this wire from the tube. It can shock you very badly EVEN WITH THE TV OFF FOR SEVERAL DAYS. Just be careful and go ahead and give this a try. You can do it, and this is probably going to fix your set. If not, then replace the flyback transformer. The H.O.T. is about $10 or $15 and the flyback can be from $30 to $80. It is possible that none of this will fix your set, but you have about a 95% chance that it will and with such a big and nice and relatively new set, I would give it a shot. Keever