Pinstripe V2.1.0 Link

The password for Pinstripe’s secret lair is 1922 , which is the date on the newspaper given by Happy.

To defeat Pinstripe, dodge his floor beams and immediately shoot the helicopters he summons. He is only vulnerable when the yellow protection circle disappears. Achievement & Secret Tips Pinstripe v2.1.0

You must find three notes. Two are in safes (breakable with the slingshot) and one is obtained from Happy in the cave after agreeing to his deal. The password for Pinstripe’s secret lair is 1922