Well, it happened to me: while Sun blade said some reasonable Mac and SystemID, they did not match.
The following helped:
Take Ultra 10 (you own Ultra 10, don't you?), power it up, then hotswap nvram chip and use mkp with system id 0x83.
It will complain "nvram is wrong", but auto-boot. Then put the chip back to SB100.
The problem came when I plugged VGA display to SB, improperly grounded.
UPD: the nvram died permanently. So I had to break the chip and install CR2032 to feed it.
The following helped:
Take Ultra 10 (you own Ultra 10, don't you?), power it up, then hotswap nvram chip and use mkp with system id 0x83.
It will complain "nvram is wrong", but auto-boot. Then put the chip back to SB100.
The problem came when I plugged VGA display to SB, improperly grounded.
UPD: the nvram died permanently. So I had to break the chip and install CR2032 to feed it.
