Thank you so much for such prompt replies, everyone!

I've actually followed kunix's advice to restore the NV right after receiving an email notification about his reply.
This has brought my GPS back to life!!!

I've already tried dasilvarsa's method numerous times yesterday.
lolypop000's comprehensive advice involves clearing the NV memory. If this is to be performed using the speedometer method, I am unable to do so, as I cannot boot into the Nuvi interface. If this is to be performed using kunix's SD card method, then this is exactly what I've done.

Upon clearing the NV, I have been able to have the firmware at 3.60, and install some miscellaneous updates such as Traffic Database, Voices, and Vehicles.

Some issues I'm still experiencing:
The model is now indicated as "nuvi 24xx". This used to be a more accurate "nuvi 2460". Are there any ramifications to this difference? Where did the 41-backup.bin come from and why did it have different entries from my actual region 41 info?
I am prompted to select my locale and language upon every boot. I was actually prompted for those AND time format, distance format, etc. until I've installed some updates. Now I am just prompted for locale and language, which do not seem to be sticking. Perhaps this is due to no maps being installed on the device (other than the base map).
I receive the following error when installing a North American Map via either Garmin Express or Garmin Map Updater: "The update is unable to determine where the specified map file should be written. Please contact Garmin customer support: http://www.garmin.com/contactsupport". This could be due to a map lock/authorization issue. I will try installing an unlocked map via 3rd party tools.
I will report back in a few hours.
Thanks again!