I just ordered a new HTC One M9, which arrived today. The ones I previously ordered came preinstalled with Android 5.0, so I just created a new Google Account (
tmp<random_number_of_random_numbers>@gmail.com) for upgrading the system to the current 6.0 version. I did not know about the Device Protection Feature, so I did not provide any additional information like a phone number or so. I just checked the system's software version and found it to already be 6.0, so I rebooted and hard resetted the phone via boot loader to have a fresh install of the current version.
Now I wanted to sign in with my real account and got stopped by the following message:
This device was reset. To continue, sign in with a Google Account that was previously synced on this device.
The problem is: I don't remember the mail address I used. I still know the password, but that alone is of no worth, as you might imagine.
Any ideas on what I can do?