LESSON LEARNT!!!

So, I took Gordon's advice (W2TTT) and started building my station on top of the concept "12-15v everywhere".

Don't get me wrong, I thank him a lot for this great idea. It truly is. but what came next was my own stupidity. 
I am only sharing my experience so no-one has to deal with this experience again .. and so we all can learn from my mistakes and double-check EVERY thing.

so here is my set up... 

I am running a power supply giving out 13.8 volts, that can easily be replaced with a solar panel or a car battery during field days and/or emergencies. 
From there, it's connected to a rig runner where the whole 12-15volts concept starts.

The rig runner is distributing to my HF radio, MY VHF/UHF radio, my 16-ports netgear switch, 12v to 5v step down module to power 4 raspberry pis, a 12v to 19v step up to power my screen, a 12v mini access point to distribute the mesh network wirelessly, and a passive POE injector for both the NSM2 node and the Grandstream VoIP phone. 

2 days ago,  I was doing some "improvements" to my station where I took everything off, disconnected everything, changed the step down module to a much smaller one, re-arranged my raspberry pis. and made everything look much better once installed on my shack shelves. 

Tested everything before I put it all together, and everything just worked fine. 
I then disconnected everything and put them on their place on the shelves (Will post pictures in next comment) and connetced everything again...

This time ..  I saw a little spark while turning on the setup.

so, i switched off the power supply very quickly.. .disconnected everything trying o find out where it came from. 

Nothing looks wrong.. started to plug things back one by one ... this time the POE injector didn't light up ... tested the fuse for it .. and it was broken.. 

I said to my self .. "huh, that's weird.. but may be it was a faulty fuse" ..  I replaced it.. started plugging everything back on the counter and everything worked just fine .. 

So, I again, unplugged everything .. and started putting everything in its final place again .. turned on the setup (after testing twice now) ... Aaaaand .. 

this time .. I hear the sound of little sparks, some weird nasty odor is coming out 

I look at the whole setup .. (still hearing the buzz of the sparks) and I say to it: "you are such a liar ... u were just working fine 2 minutes ago.. what is wrong with you?"
I didn't turn anything off this time .... I wanted to know where on earlth was this coming from ... it worked just fine 2 minutes ago .. and apparently the fuse didn't break this time ... until I started seeing black smoke coming out of my fine 16-ports managed netgear switch. 

I then turned the power supply off. I think I almost started a fire. ..

I was so puzzled. what could be the reason?

so, this time  I get my flashlight and start looking closer... 

So, finally I got it .. 
When I was testing the setup on my counter, everything was connected correctly: the switch, the radios, the raspbery pis, even the POE injector was connected the right way.. POE on left an LAN on right. 

but when I moved everything "twice" to the top of my shack shelves... I was flipping the POE injector .. .what was on right is now on left and vice versa.. EXCEPT ..  I was still connecting the node and VoIP phone on the left (now LAN).. and sending 2 Ethernet cables (now with POE injected) straight to the poor switch!!!!!!

the switch has fried ..... and now I learnt a lesson: DOUBLE CHECK EVERYTHING!!!!!!