[Q] Retrieving E-mail From Kindle... topic

Long story short... my kid broke his Kindle a ways back. He just got another new one for Christmas. We tried to register the new one, but he's forgotten his e-mail address. :\

I plugged the old Kindle into my PC and it can turn on, but the screen does not work (can't get past the initial swipe screen). Is there a way to recover the e-mail address at least, by accessing the Kindle via USB?