The fan is a very simple device. If it will spin freely with your finger or a pencil the fan should be OK. Check to see if the fan's power connector is correctly attached to the circuit board fitting as seen in the photo.
Since the fan is thermostatically controlled the problem might be with with some other component or connection.
There could be any number of problems.
Have any of the ribbon cables been disturbed? There might be a misaligned or damaged ribbon cable contact strip.
Examine the power supply electrolytic capacitors for leakage or bloating or a split at the top. If one or more capacitors are failing your ES20 might not have enough power to fully "boot up," a common problem with 2005 models such as your ES20.
Or, the Digital PCB, the "brains" of your ES20, might have become problematic. The Digital PCB is the green circuit board seen at the center. The CPU is fitted under the heat sink. The ES20 has the dreaded LSI CPU instead of the Panasonic CPU found on most other 2005 and 2006 model year Panasonics.