If your model computer is similar to mine...
Sounds like it thinks the regeneration wasn't completed. Can you advance the screen to see if the PM dropped to 0? If the PM is still up, try to get it to regen in the auto regen mode, following that set of directions.
Did both the indicator on the screen and the lighted button stay lit during the regen and then have they gone out now? Are there any error codes displayed on the screen if you turn the key to "on" but not necessarily start?
I suspect if it is still beeping you might have to call the dealer in the morning.
Please let us know what the solution to the problem was, we are all trying to get used to these new tractors!