HP EliteDesk 800 G1 USDT Powers on then off Power LED flashes red 4 times

[Phoenix_OS25]

My friend bought an HP EliteDesk 800 G1 USDT from someone for casual browsing use but it has something wrong with it. It powers on briefly for about 2 or 3 seconds, then shuts off, then the power button LED flashes red 4 times, then briefly pauses for about 2 seconds, and then repeats until unplugged. I bought a brand new power brick, and it still does the same thing. All I found about it online is that the power supply is being overloaded, but by what and is it fixable or is the motherboard dead? I have yet to remove the CPU and test it in my testbench PC but the CPU is an i5-4590s and 1 single SODIMM stick of 8GB DDR3.

If anyone has any ideas or suggestions that would be greatly appreciated, thank you. - Caleb

[TheOldMan]

From the explanation given, it would seem you have seen the manual, but if not, the explanations for that trouble code are listed on page 246

http://h10032.www1.hp.com/ctg/Manual/c04331008.pdf

Before removing the motherboard to bench test, try this

Check if a device is causing the problem by removing ALL attached devices (such as hard, diskette, or optical drives, and expansion cards). Power on the system. If the system enters the POST, then power off and replace one device at a time and repeat this procedure until failure occurs. Replace the device that is causing the failure.
Continue adding devices one at a time to ensure all devices are functioning properly

Otherwise, it could be a CPU problem or motherboard.