Often with a Linux kernel update, or even after a first install of Linux in place of Windows, Bluetooth stops working and the advice is usually to just power off your computer, wait a bit, and then turn it on again. Bluetooth then miraculously works again.
I mean the issue could also come from other things (not starting the right kernel module etc…), but very often it’s just this simple trick that makes it work again.
So what is changing in the Bluetooth device when you do this power off/wait a bit/power on trick?
You’re just trying to get the device into a known good state.
The truth is that it’s rarely worth trying to find the root cause of an issue unless it’s a frequent problem.
Something somewhere went wrong. We don’t know if it’s a hardware or software issue, so we’ll try a solution that covers both.
Powering the device off stops the flow of electricity, and waiting a few seconds makes sure that any capacitors (think of very tiny, very fast batteries) bleed off the power they’ve stored. Then turning it back on makes it go through the full startup process which is likely to result in a working state.
As a non-technical person, someone on Reddit once explained in a way that makes sense to me as an analogy. Say you are on vacation for a week. Over the course of the week you get pretty good at going from point A to point B, and can even take small side trips along the way. But one day you get a little turned around, and you find you can’t get back to where you need to go. But if someone could pick you up and return you to your starting point, you could do just fine going about your business.
What the asteroid said is 100% true.
I just like to add that when you change system drivers you’re adding a lot of unknown state into the equation, which you don’t have on day-to-day operation. So it’s even less worthwhile to debug what happened. You’re not likely to update drivers everyday.