I have a Dell Inspiron 15 (5000 series) laptop which is about two years old. About six months ago I started having issues with the 'i' key on the keyboard. I would often have to hit it more than once, or harder than usual in order to get it to come out. It kept getting worse until it became basically unusable, and eventually stopped functioning entirely. Around that time another key started to fail as well. Recently the whole keyboard has begun to have the problem though, with the exception of just a couple keys. One thing to mention though is that while the keys are hard to get out a lot of the time, there are moments where it works very well (with the exception of 'i', which is totally dead). Sometimes I barely have an issue with it, but it's very short-lived and seems to follow no particular pattern as to when it works or when it doesn't.
A couple days ago I took apart the 'i' key and sprayed compress air in there, picked out some garbage with tweezers, etc. There wasn't much in there but regardless it had no effect. I also tried power cycling which seemed to make one row of keys in particular work very well, but on restart they all reverted back to their usual functionality. I know I should obviously just get a new keyboard, but I'm not sure if it's the keyboard itself, or its connection with the motherboard, or some other issue. What do you think the most likely problem is, and is there anything else I can try?