the screen could have been black for while if windows was updating, and your computer needed a lot of memory to do the update - it shuts down things that take a lot of memory such as the screen if that happens

the fact that you could restart the computer does not sound like a battery issue to me; if windows 10 dectects battery power that low in a laptop, it usually shuts down and stays shut down until you plug it into a socket, when it can power up from the socket as normal as well as charge

so you may just have needed to wait for the updating to finish during that hour

do get your computer checked like gary said; if it is the battery it may need replacing, if it was an update it may mean some other hardare is not working as it should