I purchased a refurbished A1419 IMac from a authorized Apple Store that later went out of business. They didn’t provide me the firmware password at time of purchase. About a yr or so ago, the lock appeared, and was told to bring it in to the Apple store with proof of purchase which I did,for them to reset or remove. They later told me they couldn’t help me, because I was not the original owner. So if you’re purchase a refurb iMac, beware..my original invoice did not correspond with the original owners name. I posted my frustration on the BBB website and Apple would not do anything to help me. This should be a Class Action Lawsuit for those who may have purchased from a authorized Apple dealer/store. Any help would be appreciated