Turns on for a few seconds, turns green then shuts off.

Sounds like you have a problem with the green crt. That is the one I've most commonly seen fail first. Your tv has three picture tubes in it that can be accessed from the front of the set. The picture tubes(crts) have a filament inside the neck like a light bulb has a filament. Over a period of time tiny particles burn off and the debris can cause a short circuit from one piece of the filament to the other. The tubes are no longer avail. as a new replacement part but the tubes in your set can possibly be saved. One trick is to lightly tap on the neck of the tube with an insulated post or screwdriver handle. Right when you turn the set on and it goes green sometimes you can lightly tap on it, (the middle tube) and knock the debris free removing the short. If that doesn't work the tubes can be rejuvinated/cleaned using a machine found in most repair shops known as a picture tube rejuvinator. My experience is that this procedure should cost 100.-200. plus service call. Most service people will tell you that this is not a guaranteed fix, but 90% of the time it works and you can get years of more use from the tv. Good luck, Russmann.