Having problems with flashing screen on my ...

this problem sounds like the main video board. Try this... take the back panel off the tv and on the right side, take the cover panel off the board with all of the inputs, next, take a screwdriver and with the handle of it, tap on the tuner (this is the little shiny metal box with 1 wire and multiple connections soldered onto the main board) and see if the screen goes blue or loss of picture. Note: tv must be powered on, and with a nice clear picture in order to see results. If this is the case then you will either have to get the main board and replace it