SP-404 no longer powers up

[Synthasy2000]

I recently got two SP-404 samplers. One works perfectly after fixing the CF socket but the other refuses to switch on.

They guy I got it from says it just stopped powering on one day.

I'm a fairly competent tech and I've gone over the board checking for blow components and that the voltages are there. Everything seems present and correct.

I've even swapped the good board from my other SP-404 with the broken board and the good board works in the other unit and the broken board fails as before.

All I can think of is there's some corruption in the OS Flash ROM.
I've tried to update the OS via CF but as the SP-404 doesn't even boot it can't reinstall itself.

How can I reload the Flash ROM?

Send it off to Roland?