u/CelebrationMain843

I recently bought a used MacBook Pro 2017 (Intel, no T2 chip) from a wholesaler.

Before buying it, I confirmed with the previous corporate owner that the Mac had been removed from their MDM in 2023, so it should no longer be managed remotely.

When I first turned it on, the Mac booted normally into the macOS setup assistant. I was able to:
• Select region and language
• Connect to Wi-Fi
• Sign in with my Apple ID
• Create my user account
• Use the Mac normally for an entire day

Everything worked fine. However, the next day when I powered it on, the Apple logo appeared, followed immediately by a padlock icon with a password field. No other text is displayed.
From what I understand, this is an EFI/Firmware Password (not Activation Lock, since this model lacks a T2 chip).
What confuses me is that the Mac worked perfectly on day one and only showed the firmware password on the second boot.

My current theory:

1. The firmware password was already set by the previous corporate owner.
2. The first boot succeeded because the internal SSD and macOS installation were recognized as the default startup disk.
3. On the second boot, the startup disk may not have been detected, or perhaps an automatic background macOS update attempted to change the boot volume.
4. The Mac then automatically attempted to enter Recovery, Startup Manager, or an update volume, which triggered the existing firmware password.

My questions:
• Does this explanation make sense?
• What could cause the startup disk to be detected one day and not the next? Could an SSD issue or corrupted startup volume cause this behavior?
• Could Find My or any remote lock still trigger this even after the Mac was removed from MDM, considering I signed in with my own Apple ID?
• Has anyone experienced a Mac that worked normally and then suddenly asked for a firmware password on the next reboot?

Any suggestions on how to confirm whether this is a storage issue versus a previously configured firmware password would be greatly appreciated. (Note: I cannot reset the NVRAM because the firmware password blocks the keyboard command).

I recently bought a used MacBook Pro 2017 (Intel, no T2 chip) from a wholesaler.
Before buying it, I confirmed with the previous corporate owner that the Mac had been removed from their MDM in 2023, so it should no longer be managed remotely.

When I first turned it on, the Mac booted normally into the macOS setup assistant. I was able to:
• Select region and language
• Connect to Wi-Fi
• Sign in with my Apple ID
• Create my user account
• Use the Mac normally for an entire day

Everything worked fine. However, the next day when I powered it on, the Apple logo appeared, followed immediately by a padlock icon with a password field. No other text is displayed.
From what I understand, this is an EFI/Firmware Password (not Activation Lock, since this model lacks a T2 chip).
What confuses me is that the Mac worked perfectly on day one and only showed the firmware password on the second boot.

My current theory:

1. The firmware password was already set by the previous corporate owner.
2. The first boot succeeded because the internal SSD and macOS installation were recognized as the default startup disk.
3. On the second boot, the startup disk may not have been detected, or perhaps an automatic background macOS update attempted to change the boot volume.
4. The Mac then automatically attempted to enter Recovery, Startup Manager, or an update volume, which triggered the existing firmware password.

My questions:
• Does this explanation make sense?
• What could cause the startup disk to be detected one day and not the next? Could an SSD issue or corrupted startup volume cause this behavior?
• Could Find My or any remote lock still trigger this even after the Mac was removed from MDM, considering I signed in with my own Apple ID?
• Has anyone experienced a Mac that worked normally and then suddenly asked for a firmware password on the next reboot?

Any suggestions on how to confirm whether this is a storage issue versus a previously configured firmware password would be greatly appreciated. (Note: I cannot reset the NVRAM because the firmware password blocks the keyboard command).