Perhaps the microHD, when it sees the existing userdb.udf on the external disk, refuses to write over that file and takes no action but neglects to tell the user it didn't write a new userdb.udf.
After uploading the edited userdb.udf, I noticed the following:
1) All satellites were deactivated. So I had to activate each satellite that I use.
2) All motor drive configurations were set to No Motor. I had to re-configure each satellite for USALS motor drive.
Other than above, all was well and untouched from before editing the .udf file. The minor edits I had done were in place.
After installing the new userdb.udf, I removed the USB memory stick using the menu command for this, then I powered down the receiver, pulled the power plug out, waited 10 seconds then re-attached the power plug and powered the receiver on. I think this is a safe plan anytime you muck about doing database or firmware changes.
I have experienced the boot-loop issue so I now have the required cable necessary to get out of that situation, if I experience the issue again. If you plan to be an "aggressive" user of the microHD, you should get the cable to have it on hand.