Key cylinder lock won’t release

I replaced the key cylinder but lo and behold it ended being my 40 amp ignition main fuse in the engine bay fuse box, just a heads up.
97 Pontiac Grand Prix 265,000

I'm trying to understand what happened. It blew the 40A breaker? Or the key us stuck? What brand key cylinder? Was the cylinder for your existing key? Very interested as i may need to replace my key cylinder.