If she's like mine she's going to tell you everything is fine and when you visit her in a few months you'll see it isn't working.
I once helped my grandma, on the phone, navigate through a VCR to record a star trek episode. Everything was going well but I came home to an empty VHS.
"I told you it was fine so you wouldn't worry."
I miss my grandma more than that episode of star trek.
Talk your grandmother through anything GUI related over the phone and compare. Spend half an hour trying to help her figure out which button she should press only to find out at step 3 she opened facebook instead of the start menu, and that she actually has been pressing buttons randomly for 15 minutes while producing assorted nonspecific vocalizations of agreement while doing literally none of the things you've asked.
Or even get the legendary confusion of them never having turned the machine on in the first place.
Generally, after years of experience doing exactly this, I've found it is a lot easier to dictate a literal sequence of characters over the phone than coordinate a complex visual action with only confused verbal feedback.
Of course, with terminal stuff, you have even further options in, say, sending an email with an attached bash file for them to download and click, or if this continues, set up a script for them (and ad an icon for it in their start menu) that ssh's them into a handy aws or digital ocean instance so you can then ssh into their machine from the comfort of your own home and do it yourself.
This isn't a great example (or maybe it is considering how non-trivial the operation is), but running stuff from the command line can often be great for tech support. There is a reason support normally asks people to open things from the run dialog instead of asking them to go through the start menu.
This might be a bit too much to expect grandma to perfectly type, but "sudo apt-get update" and "sudo apt-get upgrade" to update her system is certainly easier then trying to describe what to click on a graphical UI.
