The solution requires a new motherboard?! You've got to be kidding me. That's no solution nor explanation.
I've had my mini9 since early 2009 - close to 4 years now. Recently it developed the same problem - will not wake from sleep/standby. Sheesh. And, I'm running WinXP - what it came installed with - not OSX nor Linux.
It's a pity as I believe the mini9 remains one of the most desirable wee little computers to this day. Unlike a tablet it includes a usable (just) keyboard and mouse, THREE usb ports, SD card slot and a small but brilliant display (iPad includes no USB nor SD card slot - hobbled). The OS isn't crippled as it is with some tablets.
Wonder if this is one of those planned obsolescence things, as mine failed for no reason. I didn't do anything unusual.