You are right Fran..... this is truly a disaster and I would never trust this Korg again. (imagine how you would feel just before a gig starts)
Willy just called me telling they were able to reboot after 10 minutes (!) of trying Power off/on :
It looks like they have a workaround by switching off the power again immediately after the backlight of the display starts, and then switch it on again....
No, he did not install a new OS just before this major faillure occurred.
A fuse never 'heals' and he got it to work. This could be a startup problem in the switching powersupply or the System/CPU-clock generator.
I guess the best advice is to let the dealer/distributor find out what is wrong
Roel