Xbox One S turns on and off

Hi all,

I own an Xbox One S and recently it has gone wrong. The Xbox turns on for a while and then turns off. I then replaced the power supply using a tutorial and now it does the same thing but everytime you turn it back on, it turns off quicker. When you leave it for a while it stays on for longer again but stills turns off. When it turns off, the power supply makes a buzzing noise. Any ideas what it could be as the Xbox doesn’t seem to be hot.

Cheers,

Kieran.