Facing TV Problems? Ask a TV Technician.
Hello and sorry you're having problems.
Were the symptoms exactly the same both before AND after you replaced those boards?
Also, what are you connected to on the set- have you tried more than one source (cable/SAT box, etc.) and also more than one HDMI cable?
While the screen is flashing, grab the original Toshiba remote and press MENU, does the MENU flash as well?