I've got a Qube 1 (2700WG I think) that boots up to a blinking cursor
on the LCD, no matter what I do.
The unit now has adequate power (turns out that I wasn't providing
enough amperage previously -- but that didn't affect anything) and
I've tested it with multiple drives.
I have a CacheRaQ 2 also, with a netbsd 1.6.2 custom kernel copied to
all the "vmlinux" names that the various Cobalt firmwares look for.
I've also tried yanking RAM in and out in case one stick is bad.  
I'm far from an expert at soldering stuff, so I haven't tried building
the serial adapter to see what (if anything) that says...and don't
want to spend the money on the chips yet if someone can help me out
here (even if it's just more things to try before I end up building
the console adapter anyway).

Thanks,
Michael