![Image](https://i.imgur.com/KLutvR5.jpg)
I just bought a BTC 5339R (old new stock) and found out one of the keys aren't responding. So I took it apart and stuck a new piece of foil (cut out from a crisps' bag) on that key, and that was fixed. I've looked at the circuit board in the process of fixing it, and I found that besides the keyboard controller IC, there are two CD4044 latch ICs on the circuit board. I just wonder why those two are added into the circuit?
![Image](https://i.imgur.com/iqzBnzp.jpg)
^ Here's the circuit board.
![Image](https://i.imgur.com/TroCk8f.jpg)
^ This is what I used to repair the key, in case you are interested.