I had a similar problem, the key had no conductivity acros the little black strip on the bottom of the socket. Normal range is 100-1000 ohms. You have to take the keyboard apart to fix it, lots of little screws and some unsoldering but not too bad, really. You can replace the the plunger assy from another key. You can also just replace the little black conductor by unpeeling the old one and replacing it with a good one from a spare key. I know, I don’t have any spare keys either but used the F7 key temporarily. I dont use it much anyway. I saw a good YouTube video where the guy did this very thing and now I have too.