Hello Lora, thank you for including the serial number for this forklift, as there are a few differnt models of controllers used in M40 cats, and having a serial number will make it easier to know which controller YOUR truck uses, however I do not have any referaces for a unit that old. Don't give up hope just yet though.
I would normally suggest that someone with a problem start a new thread and use the model and a very brief description in the subject of the thread (like no drive), but since we are here, let's just "go with it".
First I would want to know if the forklift still lifts, and if there is ANY sign of it trying to drive (no clicking or any other sound or motion) when you sit on the seat, turn on the key and put it in gear?
It would be my bet that the washing and trying to drive it before it had enough chance to air dry has indeed done some damage. [I hope you don't wash your TV, stereo or computer too. ;-) ]
There are a number of fuses in this unit, and it may be just a blown fuse (hopefully) but be sure to get the drive wheels off the ground and disconnect the battery before attempting any tests or repair on this unit. some minor corrosion on the contacts is pretty much normal, as they carry a LOT of electricity, and do not try to clean the corrosion off with any sort of file, just as long as they work at all.