Here's a breadcrumb for anyone else encountering this. This was the first update for the V2 (according to the messages) so my skepticism about success was high.
In spite of the warnings on the APP and RC about not powering off anything, I had to when the drone battery ran low. After a reboot of everything and a new battery, the message to update the firmware presented again and it started at 0%. Eventually it completed the transfer of the firmware and then did the install to the drone. The RC displayed an AUTEL logo for what seemed ages and I thought it had hung but eventually (like 5-10 minutes) it displayed a success message.