(1) Take out the battery / Unplug the phone
(2) Put the battery back in
(3) Turn it on and keep only Vol Down pressed
You should get a tri-color screen. Connect USB. Once it says USB at bottom, you are good to go with flashing.
Current Devices : HTC One, iPhone 5
Retired : HTC Diamond2, HTC HD2, HTC Sensation XE, HTC Sensation XL 16GB, Motorola Razr, Galaxy S2, Galaxy Note, Xperia S, Xperia V, HOX+, HTC Butterfly, Galaxy S4