It was so bad it made internet access, via any browser, impossible. Couldn't system restore or factory restore. I'm not technically savvy enough to figure out how to wipe the OS and reinstall via USB. .
Norton has a free download called the Norton Bootable Recovery Tool. This is probably what your computer repair shop used lol.
It'll fix anything, I'm surprised they give it away for free.
I'd run it if I were you, even with the clean OS.
There's a link on this page for the tutorial.
https://support.norton.com/sp/static/external/tools/nbrt.html