How to tell the difference between a firmware password and the passcode set remotely by FindMy
I have posted a couple of related questions trying to solve the mystery of a locked Mac Mini. I bought a used Mini for my bookkeeper in December. After Christmas she went to turn it on and got a message asking for a system unlock PIN with 6 boxes to enter the PIN. She asked me for the PIN and I had no idea what she was talking about as it wasn’t something I had set. After several attempts at guessing the PIN, it then gave a message that it was disabled and to try again after a minute, then 5 and then 60. I took it to the retailer where I bought it and they asked if we had set a firmware password. Again I had no idea what they were talking about. After much research, I have learned the difference between the 2. So here are my questions:
1). From what I have read, it appears to me that the screen asking for the PIN only occurs when the computer has been locked using FindMy. Is that correct? On the other hand, I discovered that when you boot in recovery mode with a computer that has been locked with FindMy, you get the black screen with the white padlock which is the same screen you get with the Firmware password. Hence my belief that I am dealing with the lock from FindMy, not the Firmware password and would just like to confirm my suspicion.
2). If I am correct about the above, is it possible that the previous owner could have locked this computer? However, when I set this computer up, I set it up with an Apple ID. When I first looked at FindMy to find the unlock PIN, it said no devices were found. Lately it does show up in the list of devices but says it is offline, even though I have it connected both by Ethernet and WiFi to our network. So could I have associated this computer with an AppleID if it was registered under someone else’s name? If I couldn’t have registered it, then the previous owner could not have locked it with FindMy. On the other hand, if this was registered under my AppleID, why can I not see it in my list of devices now? That would suggest to me that it is no longer associated with my ID. How do I determine which is correct?
3). If I can figure out how this computer got locked, then maybe I can figure out how to unlock it. And don’t tell me to take it to Apple with the proof of purchase because I tried that and they wouldn’t recognize the receipt I have for the purchase as valid, which is a whole other issue that ticks me off! BTW, if it makes a difference, when I set this up with my AppleID, it was under Mojave. It is possible I may have upgraded it to Catalina, just don’t recall. Is there some feature in Catalina that could cause this. Might there be a lock that was activated because the computer wasn’t used for several days over the holiday?
Mac mini, macOS 10.12