TL;DR If rice didn’t work for your water damaged key, you might want to open it up and scrub the circuits with vinegar to dissolve the rust.
Fun fact: This happened once more while writing this article, so it came in handy.
There’s this short and straightforward video by YouTuber nickyDoes that helped me out. A real life saver. This article will roughly contain the steps I followed to repair the key with the help of this video. Please visit his channel and subscribe!
https://www.youtube.com/watch?v=ihtKV-E_PK0
Worn out key that has gone through too much.
Step 1: Take the battery off, The lid is pretty easy to pop out.
Step 2: This is the hardest part. Pop the sides of the key fob, it can be very hard and it will feel that it’s going to break. Just do it carefully, you might need a flat screwdriver, or in my case, a toe nail clipper, to help you separate it, but be careful! this may make some indentations to the plastic.
Step 3: Remove the top part of the key fob, there’s 2 flaps on each side holding it in.
Step 4: BE CAREFUL TO NOT DROP THE LID WITH THE BUTTONS and remove the circuit board carefully.
Step 5: You should be able to see the corrosion in the circuit board. Try drying it out completely and rub some vinegar on it, this will clear the rust like magic! I used an old toothbrush head for that.
Step 6: Reassemble everything and test it out, you might have to get a new battery.
First time fixing the key
Second time fixing the key