Question MSI B450M Mortar Max - PC not turning on

[fanmoefoe]

Hi I'm in a bit of a pickle and I'm hoping for some guidance here on how to solve this issue as it might be more obvious to others than it is to me.

Specs:
B450M Mortar Max
Ryzen 7 3700X
AORUS RTX 2070 Super
Corsair 2x8GB DDR4 3600MHz RAM
CoolerMaster 750 MWE Gold PSU
XPG SX8200 Pro 1TB - connected to Mobo
XPG SX8200 Pro 1TB - connected to PCIE card adapter to Mobo

My PC worked perfectly fine since March 2020 till yesterday it was having issues turning on. Pressing the power button for the first time lights up VGA, BOOT and DRAM (CPU does not) for a split second and then it turns off. Subsequent presses of the button does nothing - until I turn off the PSU plug from the wall and turning it on again, which will repeat that split second EZ Debug LED turning on.

Events that might/not be relevant:
Night 1 - Some drips of water spilled from my AC to a USB Hub (PC is far from this so is unaffected but the USB Hub is connected to PC)
Day 2 - Day after night 1, USB Hub was working/not working, I just wiped everything dry and left it connected to my PC as it was still working. PC turned on and ran perfectly fine.
Day 3 - Turning on the PC after I woke up prompted nothing. I'm not sure if the EZ Debug LED even turned on for a split second but I only remembered it not turning on. I tried some things including taking out the power plug from PSU and wall etc, swiching to a different socket etc. but nothing seemed to work. I left it alone for a while then I just turn the PSU off and on again and boom - pressing the power button turned the PC on fine and everything ran fine. After some hours I decided to turn the PC off and turned it on again, and it turned on, everything went as they should.
Day 4 (present) - Pressing the power button to turn on the PC did nothing but turned on the EZ Debug LEDs only for a split second as mentioned earlier. Tried what I tried in Day 3 but nothing works. Disconnected some USB cables from my PC including the USB Hub, even my display connectors from GPU and it still cant turn on.

I wonder if anyone might have an idea what the issue might be? I'm wondering if the water drip to my external USB Hub was a coincidence, I'm not sure. Another thing that might not be relevant but I don't want to miss anything out - only other changes that has happened is I've just started playing Minecraft (Optifine) for a couple of weeks. Prior to this fiasco my PC was running perfectly, with no CPU/GPU overclocks - RAM was running XMP speed 3600MHz. RAM sticks are listed on the Mobo's QVL list.

Any help/tips are hugely appreciated. Thank you!

Update: Switching the power cable from another PC and turning it on managed to turn it on - but after pressing and holding the power button to shut down, and turning it back on, it went back to EZ Debug LED turning on for a split second (VGA, BOOT, DRAM) and PC completely not turning on anymore. Does this indicate PSU failure, or motherboard?

 

[Lutfij]

Breadboard the system and work with bare minimum parts. Why do you have the second SSD in an adapter? The board should allow for two NVMe SSD's to work with only on at slower speeds. Make and model of the adapter and which slot it's populating on the board?

Try and use another PSU that is reliably built to rule out a PSU power delivery issue. No, CoolerMaster MWE's aren't reliably built.

 

[fanmoefoe]

Breadboard the system and work with bare minimum parts. Why do you have the second SSD in an adapter? The board should allow for two NVMe SSD's to work with only on at slower speeds. Make and model of the adapter and which slot it's populating on the board?

Try and use another PSU that is reliably built to rule out a PSU power delivery issue. No, CoolerMaster MWE's aren't reliably built.

I'm in the middle of disassembling everything from the case but Mobo, case fans, CPU and Cooler. No extra PSU at hand to switch out, wish I had known tho that CM MWEs aren't known to be reliable. That being the case only thing I can do is just making sure all the PSU cables are attached properly - including with cable extensions for CPU, GPU and Power Pin.

One of the SSDs with adapter was a mistake purchase on my end. Advertised as PCIE Gen 3x4 adapter, not knowing u had to connect the adapter to a PCIE Gen 3x4 slot to achieve those speeds cos otherwise what would the adapter be useful for if u already have that slot on the mobo. Went ahead using it anyway as it could help with temps, not being underneath my huge GPU. This was seated to PCI_E4. The primary drive is on M2_1, GPU on PCI_E1. The SSD seem to work on the adapter perfectly fine past months but planning to remove it after this troubleshooting as it's unnecessary.

Thank you for responding. Will update and give as much info as necessary.

 

[fanmoefoe]

Breadboard the system and work with bare minimum parts. Why do you have the second SSD in an adapter? The board should allow for two NVMe SSD's to work with only on at slower speeds. Make and model of the adapter and which slot it's populating on the board?

Try and use another PSU that is reliably built to rule out a PSU power delivery issue. No, CoolerMaster MWE's aren't reliably built.

Update: Switching the power cable from another PC and turning it on managed to turn it on - but after pressing and holding the power button to shut down, and turning it back on, it went back to EZ Debug LED turning on for a split second (VGA, BOOT, DRAM) and PC completely not turning on anymore. Does this indicate PSU failure, or motherboard?