Last year my MacBook Pro developed an issue where the internal keyboard / trackpad would become intermittent. You could get it to work if you pressed a certain place on the bottom panel.
It was under warranty so eventually I sent it in to Apple to get repaired, they replaced the 'top board' and while they were at it they replaced the screen because some of the anti-glare coating had rubbed off in places.
Since it came back I had an issue where Bluetooth will just stop working, sometimes at random times, mostly about a minute after waking from sleep. Some say it's a software issue, I diagnose a hardware issue - the Broadcom bluetooth adapter (presented as a USB device) just disappears from the device list. My theory is that during the first repair it may not have been reseated in the socket securely.
So I got myself a £5 toolkit from eBay that includes the 'pentalobe' (that's a star to you and me) driver I needed to open the case, got it open, identified the Bluetooth / WLAN card, pulled it out, cleaned the contacts and put the whole thing back together again.
So far so good. I've been able to walk away and wake up my MacBook from sleep a long while later by wiggling the Magic Mouse, something I've not been able to do for months. 😀😀😀