I don't know that it rises to the level of a add on to the upgrade steps, but making sure the battery is got enough of a charge is probably a must. Would think that a power off during some portion of the process might really lead to some real problems.
Also as a helpful note, holding the right side if the button to get to the secret menu is more like 16 seconds than the 10. That extra 5 seconds before it kicked in had me starting over thinking was doing it all wrong. Just saying . . .
Love working in DOS again. Brings back all those os programs, ms-dos, pc-dos, Dr-dos. Anyone remember good old CP-M once being the cats meow for the OS?
Cheers.
Dr