"My keypad is marked 9800 and I am replacing with a 9827 keypad."
As I said before, 9800 is the Control Panel number/type, 9827 is the Keypad number/type that goes with the 9800 Control Panel.
"9800" is the overall name for what you have.
As an alarm engineer I would/wouldn't turn off the power to do this change, depends on the circumstances and my physical access to the Keypad - the choice is yours.
Remember, don't touch any of the wires together if you do it live, you'll blow the keypad fuse in the panel - best to power down both mains and remove battery in the panel.
Your programming will not be lost by powering down, there is a Non-Volatile Memory (NVM) chip that retains the programming.
Suggest you power down mains and battery (outside box should sound, don't worry about it) remove and replace the keypad, wire for wire, don't get it wrong.
Power up battery and mains, close lid of control panel then enter your code once/twice, can't remember.
Good luck, post again, I'll be around all day
acorn
January 2010