Ok, my cluster did sort of the same thing on my 620, but the needle was stuck on 11000 rpm when it wasn't even running.
Took it back to the dealer and he said the gauge cluster had a common problem with all current (before 696) Monsters. He pointed to a S4R and said that one needed to be done too.
He took it off and put a new one on, under warranty.
So, take it back to be replaced.