How to restore a PS5 that was turned off during a data transfer to another PS5?

[supercdubz]

Merry Christmas Eve all! I was gifted a PS5 and transferred save data for my games from my brother's (he had one first). Once my PS5 restarted after the data transfer, he went ahead and turned his PS5 off (despite the message telling him not to). The source console is now stuck on the "Transfer Data to Another Console" screen, no matter what we do. The destination console has no prompts to cancel the data transfer. How can we restore the source console to a playable state?