I had to hard reset my Diamond a few days ago.
Press and hold volume down and the action key,
press and hold for a few seconds soft reset button with the stylus (while still holding volume down and action),
release soft reset button but keep the others pressed until the message appears on the screen.
or read this
http://wiki.xda-developers.com/index.php?pagename=Diamond_HardReset
Press and hold volume down and the action key,
press and hold for a few seconds soft reset button with the stylus (while still holding volume down and action),
release soft reset button but keep the others pressed until the message appears on the screen.
or read this
http://wiki.xda-developers.com/index.php?pagename=Diamond_HardReset