Hi Tom,

Although I am not familiar with your Jazzy power chair, I can tell you without a doubt that you need to disconnect the batteries immediately before any (further) damage is caused to the electronic circuits.
The heavy rain has most certainly caused water to enter the circuitry and short out delicate components.
You need to disconnect the power batteries and open the controller unit as soon as possible in order to let the internal components dry out before further operation. Try using a hair drier on mild heat to dry any traces of moisture.
Electronic components are not easily damaged by water alone but will most certainly be damaged by allowing power to pass through the circuits when wet.

Best wishes,
Graemevm

You have moisture in the electronics. Purchase a can of electronic cleaner and spray all the electronic connections to remove any moisture. Make sure you purchase electronic cleaner which will remove the moisture and dry in seconds.