Supervised Mode Recovery

I was recently trying to repurpose an old iPhone 6 for my son to use with his continuous glucose monitor. I replaced the battery, so that is now as good as new.

But I didn't want to just hand him a smartphone with a web browser and other things—he's just five. Then I remembered device profiles: I could make a very restricted device profile and then it would be locked down pretty hard to only run the glucose monitor app.

I opened up Apple Configurator, created a device profile, tried to install it, and it said that the phone needed to be in supervised mode. Sure, ok. I tried to enable supervised mode. It then said that it needed to wipe the phone first. I press OK, and it starts erasing the device as a part of enabling supervised mode.

This is where things went bad.

While it was busy doing that, I went back to the profiles I had been working on and started making adjustments, while it was erasing and setting up the iPhone. At some point Apple Configurator locked up hard. I waited a while. The phone eventually booted up with the "Hello" screen. I eventually force killed Apple Configurator and tried started over. No biggie, right?

I have not been able to make any progress past this point. When I try to re-prepare the phone in Apple Configurator, I eventually always get this error:

"An unexpected error has occurred — Failed to create activation request"

If I try to activate on the phone itself via WiFi, I get the following error:

"Unable to Activate — Your iPhone could not be activated because the activation server is temporarily unavailable."

Activating via Finder on my mac doesn't seem to work either.

I tried to look into this situation, and what I believe happened is the condition warned about here:

WARNING: Preparing devices may take a few minutes. If you try to cancel or stop the process, Apple Configurator takes the time necessary to safely terminate all operations. Don’t shut down the Mac running Apple Configurator while it’s preparing devices—doing so could damage the devices.

So I think when Apple Configurator locked up that screwed up the activation state of the device. Now it's in activation lock limbo and I'm not sure how to recover.

I looked into how to get Apple to "reset" the activation, but they want proof of purchase information, and I don't have that information from back in 2014. Even if I had it, it isn't entirely clear to me if they could correct this condition remotely.

So... Did I actually irrecoverably brick this phone? Or is there something I could possibly do to recover it from this state so that I can use it again? Has anyone else run into a problem like this?