Replaced blower assembly per AO Smith. Tested blower assembly and water heater still shut off as it was originally doing. Searched through burner assembly, found burner to be out of its mounting bracket. Reset burner. Found a diffuser from flue assembly had broken off of flue. Removed broken diffuser. Found air switch on BRAND NEW blower assembly was leaking. Replaced with a new air switch and water heater is NOW operating correctly.