When running the upgrade you should have all external peripherals disconnected and sometimes you will need to disable a 3rd party antivirus program.
It's also best to ensure that all of your drivers are up to date.
You can do that to a degree by going into Device Manager/View/Show hidden devices then expand all sections and right click on all devices including those in System Devices and selecting Update Driver.
Use the default Search online option and while most will probably return that you already have the latest driver, some may get an update.
There are two ways to manually update and they are using the Update now button in
https://www.microsoft.com/en-gb/software-download/windows10 or using the same web site to create Win 10 install media after reading the instructions in how to create that media.
To manually update with install media, from within Windows open Windows Explorer - This PC - insert the media then double click on the drive.
If you are using a DVD that will start the process but if using an USB, that will open the files where you can right click on setup Application and select Run as administrator.
What did the MS techs try/do ?