Factory reset on htc one mini 2 doesn't work
Right, so I figured it out (much googling, some trial and error, more than a few swearwords).

The htc guide (and most others on the interwebs that have just copied and pasted HTC's instructions) neglect to tell you that the phone needs to be switched off.

So, factory reset instructions for htc one mini 2.


press and hold power button and chose "power off"
press and hold volume down and power button
hold those for quite a long time
You should then end up in the "three android symbols menu" Let go of all the buttons
Press volume down until "factory reset" is selected, tap the power button.
Cross your fingers.