Odd. My sysnand is also on 9.2.0-20 (US O3DS) and I can access eShop just fine. Even got rid of the stupid purple update dot from the theme store. I also have the update nag on the home menu currently so that isn't the issue. (You can remove the nag if you're scared of accidentally triggering it. Boot into the system updater app using the button combo and hit OK then I decline.)It doesn't restart, but when I entered the eShop it said I needed a software update. I don't know if that is for the eShop or the firmware. I am so paranoid about doing this because I don't want to get the update nag :\
Edit: I tried opening the eShop first then applying the patch. It asks to update.
Power the 3DS off, turn it back on and apply the patch before opening eShop. If it still won't work, shut it off and try again.