[Sprint HTC One (M7)] DonChino:
REVISTED - Did this work?!

Well, it seems this is the ONLY SOLUTION that worked for me, because I tried the Bad Boyz custom ROM that some others have suggested but it does NOT seem to work and there are "bugs" like the status\notification bar disappearing when you start to mess with the ROM. I flashed the Viper 8.0.0 ROM with TWRP and everything loaded properly except for one little "bug", which is this constant non-stop blinking NFC icon in the status bar so I might have to find another ROM. I wish I did not upgrade, so if you have ANY HBOOT under 1.61 - DO NOT UPGRADE WITH OFFICIAL ROM - because once you have 1.61 then you cannot S-OFF although you can downgrade the radio with S-ON and it is just a matter of unlocking the bootloader.

2 Notes:

1. Make sure you install SuperSU and do not rely on the Viper version, so let it uninstall any other SuperSU after installing from the Play Store. I believe the SuperSU installation will fail for you if you install through TWRP, but ViperROM should be rooted and instead install SuperSU from the Play Store if TWRP installation fails.

2. When you run "SIM UNLOCK helper" it WILL FAIL the first time, because you need to have SuperSU give it permission so make sure you go to the LOG in the options. Afterwards, make sure you close everything and remove from latest apps list. Then run again, when it fails then open LOG then hit BACK and now it will show you that you PASSED THE TEST. Then START then scroll down to SIM LOCK and wait like a minute or more because it took a LONG TIME for mine to un-freeze but then I hit REBOOT once it came back which is right there in the same list. If you doubt it, then reboot and do again but I was able to get it to work and then when I changed options in 4636 it would look for my SIM and did not give me any errors.

Anyway, I was able to follow all the steps here and the key seems to be downgrading the radio, because nothing seemed to work until I downgraded the radio version and then I tested it with both an AT&T and T-Mobile chip that I have lying around. The T-Mobile chips seem to work with no problems as others have noted, so you are able to make changes, register on the network, and set it up but I had problems with AT&T although I got farther than with any other modification. The AT&T chip will let you select the AT&T network, but you will not be able to scan for networks and you get NO BARS although it seems to be connecting or doing something although I suspect AT&T or something in the software is blocking you from connecting 100%.

So I cannot say 100% this SIM UNLOCK worked, but at least I was able to get to options that I could not get to before and I tried BOTH chips and only the T-Mobile chip seemed to work without any problems, so I suspect what others have reported is true and the Sprint HTC ONE M7 seems to be giving you problems with DOMESTIC US Carriers. I will be able to make a DEFINITIVE test in 2 months, because I am going to Peru and I might as well take this phone with me so I will test the Sprint HTC One M7 with both Claro and Telefonica SIMs down there. I will even try to update to the LATEST Sprint Official ROM to see if the unlock stays and if I am able to get GSM to work with overseas SIMs then the SIM UNLOCK worked, but you might as well not bother using it in the United States, so hopefully this will help others once I post an update after July and this will end up my "overseas" battle phone unless I pawn it off over there.

See you then...

:good: