Is it permissible for someone who intended to fast a make-up day (qada') to break their fast if sleep overwhelmed them, preventing them from having suhoor, and they fear fainting from hunger?

A fasting person is not permitted to break an obligatory fast—such as a make-up fast (qada')—except for a valid excuse. However, if a fasting person fears perishing due to hunger or thirst, they are allowed to break their fast. If you feared perishing due to severe hunger and therefore broke your fast, there is no sin upon you.