By default, a long press HTC HD2 endkey will bring up Action Screen. However, it only has 4 items there which are Power Off, Lock Device, Set Vibrate and Terminate Data Connection. XDA member, johcos came out his own Endkey Replacement for HTC HD2. It is like the previous Action Screen but with more options.
Well, you will have options like Enter Bootloader, Comm Manager, Restart Sense, Vibrate on/off, Data Connection on/off, Soft Reset and ShutDown with Endkey Replacement for HTC HD2. Remember to soft reset after install it.
Download Endkey Replacement for HTC HD2 v3 here.