Broken ram stick?

[KadriX]

Ok so I built a new pc yesterday.
The specs are:
i5 8400
XFX RX 580
2x8 sticks of hyperx 2400Mhz ram
ASrock gaming k4 motherboard
FSP Hydro GE 650w power supply
480gb ssd
2tb hdd
The pc works fine and pretty much everything is ok. I stress tested everything and everything passed. However my cpu temperature was extremely bad... I'm ashamed to say this but I forgot to take the foil off my aftermarket cooler  . Big mistake, I know, but this is the second system I ever built and the first time I used an afermarket cooler. To remove the cooler I needed to take out my ram.
Before taking out my ram I had 16 gb and everything was fine (except the cpu temperature, sorry), but after I reinserted the ram, I turned on the pc and now it works for 2 seconds and keeps restarting, a boot loop basicaly. I tried different dimm slots and I had the same result. I then tested both sticks individualy and noticed that the pc boots with one stick but not with the other. I also tested the same ram stick that didn't work in a second pc and it had the same issue. My motherboard is working properly, I know this because I inserted the working ram stick in all off the slots and it POST-ed into windows normally.

I am 99.9% sure that that stick of ram is broken.I have warranty so I can get it RMAed. 

So the thing I would like to know is how the stick broke? I tried not to touch the contacts, so I don't think it was static electricity. Was it just bad luck then?