When the HTC EVO 4G LTE got its last update from Sprint, an unwelcome passenger came along for the ride. Up to that point, all of the HBoots—HTC’s bootloader—could be unlocked and given S-Off. The newest update brought HBoot 1.15, which couldn’t be hacked through conventional means. Thus began the long, hard road to unlocking it yet again. That long road is now over.
XDA Forum Member Mac_Gyver, along with the help of a whole bunch of other members, mods, and developers, have solved HBoot 1.15 and the EVO LTE is one again unlocked.
Now the bad news. The method requires a considerable amount of both patience and expertise. Much like the HTC EVO 3D downgrade method, this is both a software and a hardware commitment. Also, you’re going to be soft bricking your phone. This is definitely not something you want to try when you have an hour left before work. It is something you’ll want to try if you have a lovely afternoon with nothing to do. Basically, you’ll be accessing Qualcomm Download Mode on your EVO LTE and flashing an insecure bootloader. That sounds a whole lot easier than it actually is.
For the full method, full instructions, and all of the associated warnings, check out the original thread.