I took the motherboard apart again as I thought that maybe the latch got beneath it, but no luck. Next I thought about vacuuming the whole working room which somehow worked!
So a tip for anyone who finds themselves in the same mess: if you lose a tiny, critical piece during your first-ever laptop repair… just grab a vacuum! Apparently, it doubles as a high-powered parts recovery tool. Who knew? XD
And I appreciate everyone's support :)
Thanks again