Power up issues.

So, I'm having an odd one...

Just upgraded my PC a couple of weeks ago. MAG tomohawk b650, 9600x, veng 5600 rgb ram, 5070.

Everything was fine until a couple of days ago.

First, my PC wouldn't sleep. Choosing sleep from the power menu always resulted a total shut down. This seemed to right itself.

Now, I'm having a much more worrying issue. After sleeping, the PC won't switch on at all. hit the button and nothing.

What I've tried:

disconnecting power switch and jumping the pins with a screwdriver. (no response)

checking all power leads/sockets/connectors, (all seemingly fine)

unplugging anything non essential.

reseating GPU and RAM.

The odd part... After fiddling about with the case for 5 mins. The power switch worked and the PC came on. This has been the case for the last two times I've tried to switch the PC on.

This made me think it's a loose or faulty connection that is getting jigged into position during checks, but then why is the failure to switch on still happening every time I sleep the PC?

The case itself is under a desk, away from being knocked or disturbed, so I don't see how a connection keeps coming loose every time it's switched off.

It definitely seems that the PC is losing power when it sleeps, as once the switch does work, the PC boots from total shutdown state. and the logs show kernal power 41.

Anyone know what could be going on here?