You must be S-off to use this.
( HBOOT is still locked and device is still S-off after flashing this )
Proper date for 1.55
No red text
Download and put in adb folder on pc.
Open command prompt.
fastboot oem rebootRUU
Wait for HTC logo
fastboot flash zip PN07IMG.zip
Once it says finished reboot with power button.
Device may not show a complete progress bar.
As long as it says finished in cmd you are good.