Chosen Solution
I tried a couple months ago to upgrade to Catalina, however my MBP rebooted automatically into the firmware password thing. I set it up a long time ago but I forgot it. My MacBook is second hand and I’ve since then been logged in with my iCloud-account. I tried to call Apple Support and explained that my iCloud-account is set-up since I’ve had bought my MBP. However they said without an official recipe they can’t unlock my MBP. I explained them that my iCloud is linked for years to my MacBook but she gave me this explanation: Imagine if your neighbor steals your MacBook and wants to unlock it and this is because he is logged in with his iCloud account and wants to prove that this is his MacBook. That is of course not possible? I said to her this is a weird explanation since you need to have the password (and 2FA auth) to log off iCloud and log in with your own account. She replied: “It was just an example”. Like what the &&^&? I don’t want to pay 70 bucks to unlock my firmware by some chip, because it’s just my MacBook so why would I go with this route. How is Apple checking with a receipt that this is actually my MacBook? Like wtf?
Sadly you’re facing a no win here. While I sympathize with your plight you need to look at this from where Apple sits. Somehow you need to prove you are the owner. Having an iCloud account doesn’t prove you owned the system in its self. Can you contact the original owner to get the Apple or authorized Apple sellers receipt. You’ll also need a notarized letter from them they sold you the system. Then you’ll have the needed proof.
