TV won't switch on from standby?

Are you able to give me some diagnosis assistance please. I am trying to repair a fault on a Panasonic TX-26LMD70A colour LCD television. The problem occurs when the television is switched to Standby on the remote. The TV goes into standby mode, but won't power on again when the standby button is pressed on the remote. I have used an alternative remote and the problem is still the same. When this happens, the red LED on the TV front blinks once every 4 seconds. The service manual suggests that it might be to do with the INVERTER_SOS and suggests checking the LCD Panel and DG Board.
I hope that you can advise me and thank you in anticipation.

David Wolfson
February 2018