Hi all, so as the title says essentially every time I shut down my pc it will not power back on immediately unless I remove the cmos battery or I unplug the psu from the mains for 15 minutes than it will power on and away it goes until I shut it down again, thus the cycle continues.

A bit of history it all started from the pc going into “sleep” from which I could not wake it with keyboard or mouse so a manual shutdown was required to get it to start again. Since than I adjusted the power settings so it would not sleep but stay on until I shut it down, a temporary workaround that was fine for a while but now it refuses to boot immediately after shutdown.

Things I’ve tried
Flashing the latest bios.
Resetting bios settings to factory
Booting with one ram stick/reseating ram sticks
Running Memtest to eliminate RAM
Removing any USB devices other than KBM than trying to power on.
Tried in another case as I thought front I/O may be faulty.. nope

Things I will try next
New cmos battery
Installing any OS updates (I turned auto updates off)
New surge protector, maybe current one is faulty and dirty power through mains causing issues?

Things I can’t try
Another motherboard
Another CPU
Another PSU
Booting without gpu as 2600x has no integrated graphics

I’m totally stumped, and Dr Google throws out all sorts of scenarios which look leads you down 5 different rabbit holes.

Specs as follow
Ryzen 5 2600x
Gigabyte b450m
16gb ram
550w psu
RX5700

Any suggestions? Thanks