I was updating four plugins, when WooCommerce suddenly failed to update, and caused my website to show: Briefly unavailable for scheduled maintenance. Check back in a minute.
A fix to this is to delete the .maintenance file in the FTP, but after having done this my site became completely unaccessible...
I get a HTTP error 500 saying that my page can't be accessed. I will contact my provider later on, but seeing as my site was working fine, and failed to update and is now offline, I can't see it as my provider's fault.