Unusual for one of these to appear completely dead, I assumed a blown fuse or a power supply failure of some kind. On investigation there was mains getting to the power supply panel but the main relay wasn’t being fired. There was no standby voltage to the main panel so it had to be the standby section of the power supply. I was working blind because, although I was able to download a service manual, there was no circuit for the power supply. I the end I found all the voltages present on the standby drive ic but the circuit wasn’t oscillating, every component around the ic checked out so it was the only real suspect. Now to source one, I didn’t want to order e replacement panel for such a small component but getting the right part is proving very difficult, I don’t trust semiconductors from Aliexpress, or China in general, so despite my best efforts it looks like a new panel is the only way to go.