Very often as blogger, you want to automatic update WordPress or update plugins.Some bigger update can create that updating proccess stop and your website become visible as :
“Briefly unavailable for scheduled maintenance. Check back in a minute.”
How to fix problem :
This message in that case can stay and you need manually to delete : .maintenance file in root directory. when you delete this file – everything will as used to be.
If you have any question about wordpress – please ask !!!
Good luck !!!