The machine does power up, but my screen remains black (no POST).
Make sure your BIOS version is compatible with the CPU generation you're trying to run in your motherboard, you can consult the manual or the manufacturer's website about this. Was working previously and board is 3000 Ryzen compatible
Check if EVERY power cable is connected. Auxiliary power connectors included. Disconnected and reconnected everything to check.
Make sure the cable coming from your monitor is attached securely to the graphics card. Also make sure it is securely attached to the monitor itself.
Make sure your PSU is powerful enough to power your complete system. 600w is overkill for system and was working before hand.
Make sure your monitor works by testing it on a different computer. HDMI input tested with Nintendo Switch
If you have both a dedicated GPU and an iGPU, try your monitor on both the outputs on the graphics cards as well as on the motherboard. No iGPU
Make sure all connectors and cables are plugged in securely, reseat if necessary. Unplugged and replugged everything
Make sure your RAM, CPU and GPU are plugged in securely, reseat if necessary. Reseated everything
If the motherboard you're using has debug LEDs, check the error code and consult the motherboard manual to see what it means. Wish it did.
If you have a debug speaker connected to the motherboard, note the beep sequence and consult the motherboard manual or this thread to see what it means. No debug speaker tried attaching an old one but no go...
Try clearing your CMOS. Tried battery and jumper methods neither works.
Try booting your computer with only a motherboard, CPU and one stick of RAM attached (if you don't have an iGPU, plug in your GPU as well ). Removed M.2, and 1 ram stick still no go...
Make sure your GPU works (if you have a dedicated one), try it in another computer. No other tower..
Make sure your RAM works, try it another computer. no other tower
Make sure the RAM is compatible with your CPU and your motherboard. Worked before XMP profile change