The only thing that i know about the hard reset is to remove the battery and leave it out for a few minutes. To get into test mode do the following: Press CLR then 073887*. Turn on Test Mode and exit the menu back to your normal home screen. Then press CLR and then left softkey to activate FTS (Field Test).
To deactivate FTS and Test Mode, repeat the steps above, and turn Test Mode to off, then exit.
You may also have some LCD problem and may need to replace it. try the reset and take it from there. One step at a time.
Here is the SERVICE manual for you
Hope this helps....