My Xbox one turns on then turns off

Check voltage on Power supply ensure it is outputting properly (if you have a meter).

I’ve seen in some cases removing the power supply (completely unplugging from both Xbox and AC) and letting it sit for a minute and trying again work as a temporary fix but usually means the power supply is going out.

If you know someone with the same unit I would recommend testing your box on their power supply.

If you eliminated that it is going to be more internal which we can work on that after the basics.

Just so I am asking all questions. Is this happened all the time or after it is being used for awhile?

Is the Power supply sitting in a ventilated area as well. (not on top of a heat vent)?