You have an engineering spl so fastboot should work fine. Soff means the safety checks are gone so all should work once you can get your phone and pc to communicate. You may want to just start over. By this I mean remove adb and all sdk folders and remove all drivers. Redownload all and when you plug in phone for first time you should see 4 drivers starting up and when plugging in while in fastboot first time 2 drivers.
Sent from my HTC Vision using xda premium
Sent from my HTC Vision using xda premium