steps to take after fixing a PC

Hi,
If you can get the media creation tool to actually work I'd try to use it to get an iso for it so you can use refresh install and keep personal files.
Otherwise it's win-10 it's already buggy :)

What I've always done is to supply a report of the actions taken, a sealed envelope containing any passwords for future emergency use, (I always print out a list of software installed and relevant passwords used as a part of the report.

Depending on what has been done I would normally supply any unused optional parts that came with any hardware fitted, and any replaced items, plus of course all documentation associated with the the hardware.

I would also normally supply a recovery kit, which would range from all or some of ... a system Disk, A disk containing any specialised Drivers added, a USB image of the working system, (including a bootable recovery option), or just a business card

The windows.old folder would be there up to a month after the install when the auto cleanup was performed so It may not be directly related to the cause of the crash

Depends on the actual history, the system may well have a key embedded in the TPM Chip, It was a requirement for the big manufacturers but they would not always place a sticker on the case. Windows Ten could have been upgraded from 8.1 or fresh installed by use of another valid key, maybe an old win 7

Showkey + is the one that seems to get the most keys from Windows 10 and related software on Windows 10 Systems. great advantage is the developer is one of our own, so will likely be around to advise

Makes sense, a lot were, I would probably run an update to check that the digital licence is activated, ( the update genuine checks will normally trigger the licence during initial contact with the servers ), It should say the status on the Settings - Activation section.

I would also suggest to the owner that they create a Microsoft account and link it to the system. They can choose to use a local account if they prefer for the normal Day to Day use, but the link to a Microsoft account can mean better support in future, (including keeping licence active after a motherboard change) - Or so the say