Facing TV Problems? Ask a TV Technician.
Since you have the 5 volts standby, this means the power supply is good and the 5 volts goes to the MAIN BOARD which processes the on/off from the remote or tact switch button and sends another voltage probably 12 volts back to the power supply which the power supply processes and turns on the inverter board and lights up the screen. The MAIN BOARD also processed the audio. CLICK HERE to see picture of an unavailable MAIN BOARD for reference and part number to match with the one in your set. I suggest a google search with the part number (if it matches your board) for price and availability. Also check Ebay where you might find a good deal.
I would change the entire board unless you have skills at taking a surface mount chip out and replacing it. Also the e-prom may not be the only problem with the board. It is a chance you might take if you chose to do so.