> [...] powering down the computer, letting it alone for 30 seconds [...]
> All this stuff costs you 10 to 15 minutes and rules out a lot.

I would also suggest burning incense and jumping on one foot
counter-clockwise around the desk chair while making chicken sounds.
The last time I did maintenance, I followed all that, and my problem
ended up solved, hence I concluded these steps helped ruling out a lot
of problems.

Bernard (Beer) Rosset
https://rosset.net/