No POST after replacing Liquid Cooling system!

Hi everybody

Few days ago when my HTPC was shutting down automatically, within few secs after booting, I found out that my liquid-cooler pump died.
I found out about it by going in to bios, I saw how CPU temperature was raising from 60F to 90F in 30 secs, and as soon as it hits 90, I think self defense triggers-in and the PC shuts down.

I replaced the liquid cooler kit with LiquidMaster Pro 120.

And ever since my PC is not POSTing.

I have tried by resetting the BIOS using the reset jumper. No luck.

My configuration:

ASRock FM2A88X-ITX+
AMD Athlon X4 880K
8GB + 4GB G.SKILL Ripjaws X DDR3 1866
MSI Gaming Radeon RX 480 GDDR5 4GB
EVGA 750 BQ, 80+ BRONZE 750W
MasterLiquid Pro 120 All-In-One Liquid Cooler
Transcend SSD 120GB
x4 WD Green HDD 4TB
Corsair Carbide Series Air 240 Case

I also have an old A4-6300 APU, which I used in this troubleshooting steps.

Following condition was consistent thru out the tests:

The tests were done on a wooden table without the stand-offs.
No HDD connected
4GB memory on bank A1
no memory stick on B1
No CMOS battery
Motherboard speaker connected.

Step by step my tests are:

#1
With A4-6300 APU and no graphics card installed, screen connected via VGA cable.
BIOS came up

#2
I repeated the same test, this time I disconnected VGA and connected to on-board HDMI before booting,
No POST.
Than I just plugged in the VGA cable (without rebooting) to see if BIOS was coming up on VGA;
No POST

#​3
​I​ re-tested by connecting to VGA only before booting, just like #1
BIOS came up

#4
Than I connected the VGA card (MSI RX480 4GB)​, but kept VGA cable connected to on-board VGA
No POST

#5
I kept the VGA card connected but just disconnected the 6 pin PCI-E power from the video card. Screen is still connected to on-board VGA
BIOS came ip

#6
I removed the external VGA and the memory stick.
I got 3 beeps

#7
I installed the memory stick back.
I replaced the APU with Athlon 880K CPU. Installed the MSI RX480 with 6 pin power connected.
No POST
Repeated the test for either HDMI port on the graphics card.
No POST

(This MSI RX480 has 2 more DisplayPorts and 1 DVI-D port which I did not test)

#8
I removed the graphics card, and the memory stick
3 beeps

#9
I installed the memory stick, but not the graphics card
5 short and quick beeps.


​My tests ended here.

Is my Athlon CPU (880K) fried? (based on #7, #8, #9)
No visual burn mark or bent pin though.

Is my motherboard partially messed up? (based on: #4, #5)​

Did my graphics card (RX480) die?

Is my PSU loosing its power?!! (based on #5)

P​lease advice.
Thank you