Fatal error after interrupting an update

I accidentally navigated away from the page while some plugins were updating.

Now, I can’t see anything in my Dashboard, nor log back into it (if I’m logged out I can’t tell as I can’t get the Dashboard on my screen) and can’t see my website. All I get is a warning and a fatal error displaying on screen (see below). I will also mention, that before I started getting those messages, for a few moments I was getting the “Briefly unavailable for scheduled maintenance” message, so I waited a few minutes, thinking that as I hadn’t actually logged out, perhaps the updates were still running and would complete normally even though I had navigated away from the page. But then the warning/fatal error messages appeared when I tried again.

It’s not my browser cache as I get the same result in different browsers and on multiple devices, some of which I hadn’t used before this error happened.

What’s the easiest way to fix this? Restore a previous backup and go from there? Uninstall and start again? or is there an easier fix?

Here’s what I see on screen (and yes, JetPack was one of the plugins I was updating, but I’m sure it was me, not them!)

Here’s what I now see on screen:
Warning: require_once(/home/davidsdu/public_html/wp-content/plugins/jetpack/sync/class.jetpack-sync-actions.php): failed to open stream: No such file or directory in /home/davidsdu/public_html/wp-content/plugins/jetpack/jetpack.php on line 76

Fatal error: require_once(): Failed opening required ‘/home/davidsdu/public_html/wp-content/plugins/jetpack/sync/class.jetpack-sync-actions.php’ (include_path=’.:/opt/cpanel/ea-php56/root/usr/share/pear’) in /home/davidsdu/public_html/wp-content/plugins/jetpack/jetpack.php on line 76

Thank you for any help.