buster/sid isn’t quite enough to know what version you are running. The version number is usually part of the image name you downloaded when you installed Debian.
We wouldn’t expect this behaviour on any version of Debian. Certainly it’s never been seen on the lastest release image (18.01, #359) and I was running the most recent snapshot for long periods over the Christmas holiday without any problems.
So whilst we need to double check the version number there is definitely scope for this to be a hardware problem… tell us about your power supply (spec, is it new, do you have a spare you can try instead)? It sounds weird but we find that power supplies are often one of the most fragile components (the smoothing capacitors in a power supply have a very tough life ).