Question First RAM stick of multiple kits in PC seems to not post in any configuration

[DislikeOfUsernames]

Hi, I recently built a pc (5900x, 6800xt, MSI B550 tomahawk, 32GB 3600Cl16 G.Skill RAM) (specifically F4-3600C16Q-32GVKC at first).
When I tried to boot at first, nothing happened (failed to POST), so I tried swapping out different ram sticks. Eventually, I found out that the first DIMM I put in the first slot no longer worked in any slot, however all the other modules worked in all the other slots, in any configuration, as well as with xmp enabled (I was unable to ever try enabling xmp with the first stick, it was more just to test stability of what I had that actually worked). Because all the other DIMMs worked in the first slot, I decided to send the kit back and order new RAM. I bought 2 kits of F4-3600C16D-16GVK (I got a refund from the quad channel kit and these dual channel kits were on sale). I only just tried using them about an hour ago and I'm worried there's some other cause of the problem, as the exact same issue occurred, with the first DIMM not working, but then all the other 3 work fine in all the slots (including the slot that I put the first DIMM in).

I don't really know where to start now and haven't been able to find similar threads with this issue. Also, I'm concerned whether to use the PC at all, even though it seems to work fine with one of the kits in slots 2 and 4. (I managed to set up windows, but have stopped using it entirely since)

 

[DislikeOfUsernames]

I forgot to add, when I sent back the first kit (F4-3600C16Q-32GVKC) they found the same issue as I did, where the PC wouldn't POST with it.
I have also not tried memtest or any software to diagnose whether it is the RAM, as it doesn't POST, I didn't see the value in trying to test the bad DIMM.
My testing has just been by swapping out different sticks and seeing what does and doesn't POST.

By the way, I am assuming that it is outside of normal likelihood that 2 out of the 3 kits I got were just dead on arrival, please correct me if this is all nonsense and I should just send it back and try again.