I've always heard about this, but never had it happen.
While flashing OBP firmware power went out and the machine was unbootable
after that.
I moved the jumper from the default low booting position to the high
The machine started working great again!

So I flashed it again which erases and reprograms the high and low sectors.
The flash was successful.
I even had the machine connected to an UPS so no power loss could happen.

After the flash was good I tried moving the jumped back to the low position
and it didn't like it.
Does the jumper need to permanently stay in the high position now?

The only thing I haven't tried yet is to find an old version of the firmware
and flash before flashing again with the newest OBP.

Any ideas?