This was just ready to go off when I got your last post.
First, I’ve checked that we have continuity to the transformer on the front panel.
The fan is 12v and I’m getting a steady 11.9v at the header, so I assume the fan is faulty. I can try another 12v fan I’ve got lying around, but it has a different plug so would need snipping the wires.
Coin battery is showing 2.8v.
Sorry you took the trouble to get the manual, I have it here. Of course, the last time I flashed the firmware, I had the front display, but I pretended just now I was going to do it again. The procedure is power: down at the back – “cold on/off” they call it, then power back on and hold down the power (standby) and OK buttons. This stopped the SATA drive, but we still had the 5VS voltage and 2.4v at P/S. If you think this is worth pursuing, I suppose I have to put everything back together and connect to TV and/or PC.