and just for a little less to think about and type, a check action rulebook automatically proceeds through all the rules unless one fails (normally with stop the action or with the instead phrase). So you can skip the continue the action (though it could be useful in a more complicated check rule with nested if-thens).
Typing it on is an action applying to one number and one thing.
Understand "type in/-- [number] on [thing]" as typing it on.
Check typing a number on something (called the peripheral) when the peripheral is not the safe:
instead say "That wouldn't do much."
Check typing a number (called the PIN) on the safe:
unless the PIN is the security code, instead say "Nothing happens."
Be cautious with messages like Mrs. Hart shoots you a confused look. 'Uh... I'm not going to ask.'". What if she’s not there? What if you type on yourself? What if you type on Mrs. Hart? (Why, yes, I’m playtesting a game currently.)
The instead can go at the end of a phrase instead (see what I did there?). It may sound stilted as English to put it first following an unless clause, like above, but my habit is always putting it first. (A comment by Zarf on instead placement called my attention to the relevance of having a habit on the subject.)