Question AORUS Z390 Pro WiFi with i9-9900K – CPU Light Turns On, System Shuts Down – Help Needed

[Electro-Shock]

I am having trouble getting my system to start. I purchased this setup from Facebook Marketplace yesterday, and I am unable to get it to boot.

System Specifications:

• Motherboard: AORUS Z390 Pro WiFi
• CPU: Intel Core i5-9900K
• RAM: Corsair Vengeance, 2 sticks of 16 GB each
• Cooler: NZXT Infinity Mirror Liquid Cooler
• Power Supply: 850W Gold-rated

Issue:
When I connect the system to power, the fans and cooler light up, and the red CPU light on the motherboard briefly turns on, then goes off. Immediately after, the DRAM light turns on, and the PC shuts down. There is no display output on the monitor.
What I’ve Tried:

• Removed and reseated the RAM sticks
• Tried using one RAM stick at a time in different slots
• Reinstalled the CPU

Despite these attempts, the issue persists. Any guidance or suggestions would be greatly appreciated.

 

[Lutfij]

Welcome to the forums, newcomer!

Power Supply: 850W Gold-rated
850W is the advertised wattage of the PSU, what is the make, model and age of the PSU?

Does your platform have a discrete GPU? If so, please include that in your spec's list. With that being said, remove the discrete GPU and see if that changes your issue.

Do the tubes for your AIO get warm or hot to the touch?

 

[Electro-Shock]

The power supply is Corsair RM850, It looks fine from outside possibly used for 2 years
No I don't have GPU right now.
AIO tubes - they are not hot.