Is it obligatory for someone who performed Hajj Qarin (combining Hajj and Umrah) and circumambulated the Kaaba (Tawaf al-Qudum) and performed Sa'y and shortened their hair, then remained in the state of Ihram, to complete their Hajj?

There is nothing upon a man who entered into ihram as a qarin (combining Hajj and Umrah), performed tawaf and sa'i, and then shortened his hair out of ignorance, because what he did was a result of ignorance. Prohibitions committed out of forgetfulness, ignorance, or compulsion entail no consequence.