Pretty much all modern chains are not meant to be broken and pressed together again.
the modern chain is Only made to be shortened , then Joined By a Quick Link . Or a high end chain tool that expands the rivet Head again
to Be tight into the link plate hole (Rohloff, Campagnolo tools )
the hole in the side plate was stretched to get it off, the Chain making machine expanded rivet head, pin ends ,
It can never be more secure than if left alone, as it came out of the Box.
Chains back in the 5&6 speed era had pins that stuck out wider than the outside links , now(except for 1 speeds) they have to not stick out at all .