5.11.1540.9 Signed Firmware.zip:
link (mega.co.nz)
MD5: ef0cc76134c170e4230804ca1c9edf02
thanks to @rc420head for testing this firmware.zip on his phone. See results at post #1045

5.11.1540.9 TWRP Nandroid Backup:
link #1 (mega.co.nz)
link #2 (androidfilehost.com)
link #3 (dev-host)
MD5: e565b0ebba873222dabbfc55376cb187
------>After you have restored the above nandroid backup, do a factory reset right away<------

You flash above files at your own risk, I'm not responsible if you brick your phone
i.e flashing the firmware incorrectly like some pple did

edit: AGAIN::
Do not flash the firmware if you don't know what you are doing!
I.e: flashing a 5.XX.XXX.X firmware over a 3.XX.XXX.X firmware WILL brick your phone ---> QHSUSB_DLOAD
If I've helped you, please hit the ''tanks'' button
If you want a reply, quote or mention me using @alray

Useful links for the HTC One:
nkk71's SuperGUIDE to returning 100% back to stock
Flashing requirements chart by nkk71
HTC1Guru.com by crushalot