Potentially dead motherboard after replacing stock cooler?

[Orbit Storm]

First, hardware specs:

- MSI 760GM-P34(FX)
- AMD FX-6300
- MSI GeForce GTX 950
- 2x 8GB G.Skill RIPJAWS DDR3 1600
- Corsair CX430 PSU

Recently ordered the Hyper 212 Evo to replace my stock cooler as my CPU was having some awfully warm idling temps (40-50 C). I went through the standard process using this video. I did have to clean the CPU and heatsink twice because I initially seated it facing toward the RAM but realized the fan wouldn't fit so I removed the heatsink, cleaned both the processor and heatsink, then seated it facing downward toward the GPU (exhaust would be toward top-back of case).

After everything was installed and plugged in, I turned the system on but never got a POST beep. All LED case lights turned on, fans were running for the power supply, video card, case fans, and new cooler.

These are the troubleshooting steps I've taken:

• 
  - Ensured all pins are connected: 8-pin for motherboard, 4-pin CPU, and new cooler fan pin.
  - I removed/replaced the CMOS battery.
  - Reseated the RAM sticks.
  - Removed the cooler (without cleaning off paste) and turned on system, still no POST.
  - Removed remaining thermal paste, still no POST.
  - Removed the processor, cleaned up any lingering dust, checked for bent pins, reseated it.. still no POST.
  - Removed RAM sticks entirely to see if mobo would beep about it but still nothing.

To be clear, I never removed the processor while cleaning. I was gentle and careful not to spill any liquids. I'm fairly certain that I seated the cooler properly and if that had been the issue, just removing it would have allowed the system to POST (to my knowledge).

At this point, I feel it's safe to assume the motherboard is dead but perhaps there is something I've overlooked. Absolutely maddening because I assumed replacing the cooler would be a boon and it's seemingly the end of my system.

 

[Sedivy]

Technically, on newer boards there should be indicator lights to blink/change color when particular parts fail but...on prebuilt system you're unlikely to have these. Sometimes they'll be beeps on startup to indicated an issue. You don't mention them so I'm assuming it's not a feature or it's nothing addressed by the beeps. Otherwise, you pretty much need different memory, cpu, gpu etc, that are known to work, to plug into it until it's confirmed that it's completely dead (ie. repair shop).