Unlocked AT&T Branded - safe to apply 4.23.617.1 to move up to Nougat?

[legionnaire2]

I have an unlocked but carrier branded AT&T HTC One M9. I've got it up to Marshmallow. While waiting for AT&T to certify and release Nougat, I noticed that the HTC One site has the Nougat Rom for Unlocked HTC One M9s here.

1. Has anyone applied this to your AT&T branded unlocked M9?
2. What issues do I need to watch out for?
3. If I run into an issue, how do I revert to Marshmallow?

 

[foxbat121]

What exactly did you unlock? SIM unlocked? If so , you are still salved to AT&T's release. You will have to convert into Developer edition to be able to apply the releases posted by HTC.

 

[legionnaire2]

What exactly did you unlock? SIM unlocked? If so , you are still salved to AT&T's release. You will have to convert into Developer edition to be able to apply the releases posted by HTC.

Correct. The phone is SIM unlocked. Pardon my naivete, but do I follow a procedure like the one outlined here to convert to the Developer edition?

Presumably this voids any warranty that HTC offers on the device? I just bought this a couple of days ago, and want to understand what I am getting into before going too far down this path.

 

[foxbat121]

Of course, warranty will be voided if you flash anything other than AT&T version of the firmware. And the process could also bricked your phone completely. So, do it at your own risk.