2 pairs of Sennheiser PXC 550 headsets bought from Facebook Marketplace for $50 for the pair (currently retailing between $2990 and $399 a piece - https://www.amazon.com/Sennheiser-PXC...)

Complaint 1 - Will not turn on
Complaint Set 2 - Will not turn on and Bluetooth pairing button is stuck

Can I fix it?

This is not a tutorial video!