I didn't want to risk both USB sticks being in at the same time so I turned the Lenovo X61 tablet off and stuck the smaller 250MB USB stick into the left USB slot and booted up the X61 (and did it again with the larger 4MB USB stick -- both worked fine to boot into the BIOS update program).
There was a bit of ambiguity since the word "BIOS" was never mentioned ... here's what happened when I powered the X61 tablet up with one USB stick in the left-side slot:
- First, the familar ThinkVantage screen popped up ...
- Then a vaguely reminiscent (from long ago) blue Win98 screen flashed momentarily
- Penultimately, a black screen asked me to "Type the name of the command interpreter" to which I responded with "command.com< enter >".
- Lastly the "Main Menu" came up asking me to "Select One", of the three options:
1. Read this first
2. Update system program
3. Update model number
After reading the (nearly useless) information in option #1, I rebooted to Ubuntu and re-read all the posts in this thread and I realize that option #2 is probably the one that needs to be executed. (You might want to make it clearer which option to execute since NONE of them say anything whatsoever about the BIOS being updated.)
Anyway, I tried this both with the smaller 250MB USB stick and the larger 4GB USB stick with the same results. It failed, but not due to a fault of yours or mine. It seems that the "update system program" command noticed the totally dead battery (which has been dead for quite some time) and will not execute for fear that a power interruption will cause a problem.
Specifically, the system-program update stated:
"ERROR: Your battery needs to be charged to avoid an accidental power-off during an update. Turn off the computer and connect the AC adapter to charge the battery".
Of course, that won't work as the 14.4 volt 4300 Ah battery has been "charging" for months to no avail as I run off the 20 volt 4.5 amp AC adapter and the (dead) battery plugged in but useless; so I'm going to have to order a brand new battery to go any further. Thanks Mike for all your help. Sorry to be a pain. I hope other Linux newbies benefit from the specific steps I listed of your more general commands.
I'll update this thread after I order a new battery and try it again when it arrives and is charged up.