It was fine this morning - put it on the charger and just took it off and now all I get on the screen is the hourglass for 2 seconds, then the red light in the upper right corner for 2 seconds - it is continuously doing this now.
First try by leaving the battery out for about 30 minutes. Insert and try again.
If no change, you may be up for a wipe with JL_Cmder to reload the OS. See the http://www.blackberryfaq.com/index.php/Main_Page for details and instructions.
Just for the heck of it - take the SIM card out (leaving the battery out during this process), clean the contacts with first a pencil eraser, then an emery board (not too hard), then a cloth (not paper towel) with a little alcohol - give it a few seconds to dry, then reinsert it, put the battery back in & fire it up.