Method 1: Keyboard
Hold down the Orange, “R” and “Sym” keys simultaneously.
I learned this method from the Sprint customer service when they were helping me transfer my old number over to my Palm.
Method 2: Power switch
Hold down the power switch and toggle the Ringer Switch (next to power switch) 3 times. I’m not 100% sure but this method seems to turn off the unit immediately without saving anything, then booting up.