A mother is telling her kid: 「お風呂わいたから入っちゃって」. From the context, I am guessing it means "The water's heated up, come in (take the bath)!".
I don't understand how「入っちゃって」 could mean a request / command here. Is 「っちゃ」is short for 「しまう」or 「ては」? Neither makes sense to me here. And what is the role of the final「って]?