Keyless remotes make life simpler, but accidents happen. It goes into the washing machine. Your toddler drops it into a glass of soda. It falls into a puddle. Don't panic. If you act fast, you can fix it.
Grab a Rag
Attempt to dry your wet keyless remote with a rag as quickly as you can. Turn it so that the buttons face downwards. Dab it with a rag and try to shake the water out of the cracks. When there's no more water seeping from the inside, try it out and see if it works.
Change the Battery
Next, open the remote. Don't force it. Look for a groove or coin slot. Or tiny screws holding the fob together. If you can't find these, use a screwdriver to ease the casing apart. Remove the battery, but don't replace it just yet; you need to dry the inside of the fob which houses a radio transmitter and possibly a chip that controls the car's ignition. The best thing to do is place it in a plastic bag with some bags of silica (you get these in new handbags or shoes; save them).
Replace the Battery
Wait three to five days. Replace the battery in your remote, gently close the casing and try it out. If it doesn't work, you'll have to contact your dealer and ask them to program a new one.
What Not to Do
Don't use a hair dryer on the keyless remote. If you don't have silica, leave it in a warm dry room for a few days. Don't put it in a bowl of dry rice, and don't be heavy-handed with it.