1. Hello. Please press the Power button to turn your phone on.
2. Now press & hold the Volume Down and Power button for a few seconds.
3. Let go of these buttons when a HTC logo shows on screen.
4. Use Volume buttons to select Bootloader. Confirm with Power button.
5. Select, in the same fashion, Boot to Recovery Mode.
6. Wait for an Android image to appear on screen. When it does, hold down Power button and press, just once, Volume Up.
7. While holding the Power button press the Volume Up once.
8. Good job, you are in Recovery mode. Navigate it with Volume buttons; select options with Power button.