Keyboard skipping keystrokes

I have a Dell Inspiron 15-3567 laptop with Windows 10 that is about three and a half years old. The other day I noticed that the keyboard was acting very strangely. It skips keys as I type. This isn't happening with one key in particular, but the keyboard in general. I have to press a key several times before it responds. To give you an example, when I type freely, 'the quick brown fox jumps over the lazy dog' becomes 'The quicwn foj pmsver the lazydog.' Yeah.

The computer has episodes where it’s way slower than normal and programs fail to respond. Sometimes it has moments of lucidity where everything seems fine, but then it starts acting up again. I’ve opened MS Word in safe mode, but that doesn’t seem to improve the keyboard. Sometimes it beeps randomly as if it's crying out for help.

With the keyboard issues, I reasoned that it could be a driver issue and tried updating the keyboard drivers in Device Manager. Windows informed me that everything is up to date. Fine. I tried uninstalling and reinstalling the drivers. Nothing. A full virus scan on Avast turned up nothing suspicious. Sticky keys aren’t on. I dusted the keyboard and cleaned it thoroughly.

This may or may not be relevant, but I recently discovered a crack in the left side of the laptop and noticed that the left hinge is loose. I tried tightening the screws, but they just wouldn’t go in properly. I ended up duct-taping the whole side since the loose screws were compromising the integrity of the entire frame. I cut out holes for the vent and it is not blocked in any significant way.

Any suggestions would be greatly appreciated since this thing is driving me bonkers. Thanks.