Ansmann w5 won't bind
 

I was using my buggy on the beach and it was running fine. Got it home and left it to dry and now it won't work, it goes into the fail safe position when remote and rx is on but won't bind when I try to rebind it to the remote. Circuit board in rx looks to have some white crusty residue on it so I tried to scrap it off but it still won't work. Please help