Dell Inspiron 1420 keyboard not working

Firstly I've had this laptop for about four years now and haven't had any serious issues with it. I'm not entirely sure how it stopped working in the first place. The keyboard cover had come off and I had it with me in the bathroom playing music while I took a shower so there was steam in the air. I've done this many times before - like when taking a bath - for an hour and everything would be fine but I'm guessing that not having the keyboard cover did some damage. Anyway, when I plugged in another keyboard via USB I noticed that everything was fine but the keyboard. So I ordered a new one and when it arrived I replaced it. I also took this opportunity to remove the screen and fix one of the hinges which is why the keyboard cover wasn't on in the first place. I'm using the laptop now with my other keyboard and everything is fine except the keyboard STILL isn't working. This is the new one now by the way. I've taken it off and on so many times. I've looked on Device Manager and it comes up as working properly and being plugged into the keyboard port. So I know it's being recognised but I just do not know what to do. I un-installed the driver and re-installed it via the Device Manager and it still isn't working. I've made sure I'm up-to-date on my Windows Updates and now I am truly stuck! Does anybody have any suggestions?