Your Psu is dead.
Borrow a Psu from a friend and try it but yours is dead. I'm sure.
Your Psu resistance could be burnt. The Psu will still send electricity to your other components but it won't power up.
This is what happened. Your pc don't have or if it has it you didn't turn of the switch to block electricity from getting in your Psu. Any electronic anomaly issue during the night made it explode or burn.
Your pc keep recieaving electronicity but the power supply lost it's potential to be able to power up your pc.
Lucky you if it only took your Psu and not any other hardware.