To close the loop on this, I purchased a DMC-FZ1000 replacement motherboard from Encompass (Part# SEP0093AA). Here's the link: https://www.encompassparts.com/item/10298894/Panasonic/SEP0093AA/Pc_Board. It took nearly a month for the part to arrive, but it eventually did and was in excellent, unused condition. It was easy to swap out the motherboard following the instructions from the iFixIt site. Anyway, I should have added this information sooner. I hope it helps someone out there.