Whilst waiting for the PS3 to arrive, I decided to pull out my old Belinea 101715 and see if there was any obvious reason that none of the buttons worked any more, and that includes the power button.
The button board seems to be just a simple switch board with nothing on it but switches, and removing it confirmed that other than the power LED, it is just a series of switches. I'll test it regardless, but I can't imagine it being faulty.
The display still sort of works, in that any VGA signal applied to it does get displayed if it's powered on after the signal is connected, but because the menu isn't available, there are no options for auto adjust, so you get what you get.
This is the board:

- PXL_20230502_080220390.jpg (345.59 KiB) Viewed 1323 times
Not sure if anybody recognises it, it's a DALM/SMB4D6 Rev 2. I have looked online but so far coming up with blanks.
It does have a Winbond W39F010P-70B chip, which is a 128Kx8 CMOS flash memory, and I'm wondering if that is dead, or had a configuration that is now lost. It's in a PLCC socket, so I've pulled it and cleaned it, but no change.
My worry is that the Winbond IC stored all the config for the menus etc, and without that, even with a new IC it wouldn't work. I may order one anyway, I can't imagine they are too expensive, so it'd be worth a punt.
It's been a very handy display over the years, be a shame if it couldn't be resurrected.