1. Used Teensy on black padlock screen over night and worked out the code.
2. Entered correct code, boots up...
3. Boots into white screen that says "Your computer is disabled. Try again in 60 minutes".
4. After 60 minutes of waiting, it immediately says 'Wrong Passcode. Try Again", but there is no boxes to key any digits into.
5. I wait a while, but nothing happens, so I restart.
6. See Step 3.
Interestingly, the only recognised startup key is option key, and while this may appear useful, when I select an external drive, it appears to want to load it, then goes back to the progress bar which then brings me back to the white "Wrong Passcode" screen.
I can't boot into verbose mode, or single-user mode, or even zap the NVRAM (P-RAM).
Has anyone got into this futile loop and give me a hint on how to get rid of it?
Also, what is the difference between a black padlock screen, and a white one?
perthdave wrote: 1. Used Teensy on black padlock screen over night and worked out the code.
2. Entered correct code, boots up...
3. Boots into white screen that says "Your computer is disabled. Try again in 60 minutes".
4. After 60 minutes of waiting, it immediately says 'Wrong Passcode. Try Again", but there is no boxes to key any digits into.
5. I wait a while, but nothing happens, so I restart.
6. See Step 3.
Interestingly, the only recognised startup key is option key, and while this may appear useful, when I select an external drive, it appears to want to load it, then goes back to the progress bar which then brings me back to the white "Wrong Passcode" screen.
I can't boot into verbose mode, or single-user mode, or even zap the NVRAM (P-RAM).
Has anyone got into this futile loop and give me a hint on how to get rid of it?
Also, what is the difference between a black padlock screen, and a white one?
Thanks,
David
Resetting NVRAM
Shut down your Mac.
Locate the following keys on the keyboard: Command (⌘), Option, P, and R.
Turn on your Mac.
Press and hold the Command-Option-P-R keys immediately after you hear the startup sound.
Hold these keys until the computer restarts 3 times and you hear the startup sound for the third time.
Release the keys.
I've tried to reset the NVRAM but I get the padlock on the black screen seconds after the startup chime. The only startup key it appears to recognise is the Option key, which will allow me to select the boot drive. The drive is labelled 'EFI' when at this stage.
If I'm at the boot selector and connect an external drive which contains a bootable image, it will give me a ø symbol after I've selected one and go no further.
If I connect an external drive which contains Time Machine backups, it will begin to boot off it, then eventually I will hit the white "Your computer has been disabled" screen.
I was able to get rEFInd to be recognised and boot up, but when I selected "boot in single user mode" (or any of the others), it inevitably wound back up at the white screen with the 'Your computer is disabled. Please wait 60 minutes and try again" window, which is ironic because it never gives you a chance to enter any numbers in as there are no text fields to do so.
I then booted into the EFI Shell, and after using Help to list off all the available commands, I decided to have a look around the NVRAM using the dmpstore command. I couldn't garner much info from here. It's a shame you cannot wipe the NVRAM from the shell, but oh well.
As I have a 15" retina of the same year, I decided to swap the PCI-e cards and see whether I was able to boot from another one, but same story, it goes through the usual (and unusual) boot sequence and I get to the white screen again.
Is there any other way I can wipe the NVRAM? Is there some way of telling the boot sequence to execute this command?
Is there a physical NVRAM battery that I can somehow disconnect? I believe the NVRAM battery is fed from the main battery in the laptop. If I disconnect the main battery from the motherboard and leave it dormant for 2 weeks, will it be enough time to have wiped the NVRAM due to a depleted NVRAM battery?
once the iCloud lock is invoked, the lock is linked to the hdd (ssd) somehow. changing the hard drive will give you the (/) symbol, as well as changing the contents of the original hdd/ssd.
the only other way to blast it is to flash it with an SPI programmer of some sort, or to replace the chip with a preloaded chip.
the rEFInd method works. if you're having trouble, try redownloading and rebuilding your USB. i had struggles with it once, but it was so long ago that i don't remember exactly what fixed it. what steps did you take to create your refind?
Additionally to what I said earlier -- after removing the PCI-e card -- I then had the option to do an Internet Recovery, but my hopes were marred when I, yet again, hit that white "disabled" window.
I'm happy with flashing it but can't locate the EFI chip on the top of the board. Is it sneakily on the underside perhaps?
The EFI chip on that model (assuming it's like the emc2865 in working on) is in fact on the underside of the board. It's also a surface mount chip with no accessible legs. It could either be interfaces with via the service port connector (with the correct 12pin mezzanine connector, a hirose piece) or removed from the pcb.
The rEFInd method surely works, I've done so myself countless times and recently assisted another user with such.
Any OS X be it install, install media, or otherwise will inherit the lock from nvram. If your rEFInd isn't correctly launching SU, I would recommend rebuilding your stick.
With ALT held down and both the refind USB and the installer USB in the Macbook select the USB EFI boot and wait for the refind menu.
You should now see the option for the Mac OS USB installer highlight it then hit F2 option single user.... wait and type nvram -c
NOTE: you should make sure your MAC OS USB is working first . They can be fussy on dates if you made it a long time ago it will hang.
If it hangs set your date back to when you first made the installer.
FYI : before i made the refind USB i tried a Windows8 install CD it booted and was able to get to the command prompt. Every Mac USB image or recovery failed with icloud lock screen.
Maybe we should write a tutorial for this process.
It's true that until you clear the nvram, you will not be able to fully load OS X in any form. Only single user.
Like ggltech noted, it's important to be sure that your rEFInd boot option is perceived as an EFI boot device, otherwise it will crap out and either load OS X normally or drop back to rEFInd boot menu.
If you're running into date issues, from the single user prompt type
date
It will display your system date. If that date is incorrect, type
date 0719XXXX2016
Where xxxx is the time in 24hr format
Yeah, it's that exact model that you're working on. I was hoping it could be flashed via that mezzanine connector, but is there an interface out there that will fit it?
As I didn't have a USB stick handy, I burnt the image on to a CD and booted from an external SuperDrive.
Maybe your SSD drive needs reloading....single user or boot OS is corrupted. EFI tries but reverts to lock. Erase and restore it using your other macbook.
Then try again.
scratch that thought....i think the single user mode is loaded from the install media not the SSD.
Try your refind and install USB media setup on a working macbook ..see if you can get into single user mode .
Hey again, I finally got it to boot from the install media (I was mistakenly F2'ing from the other USB, hence why I was getting nowhere).
I booted to single user mode, til I got to the prompt, where I then entered -> nvram -c and hit return. It waited a moment then carriage-returned to the next prompt. I then restarted and held down the option key. The padlock came up, I entered the 4-digit number, it boots, then eventually, it goes to the white screen.
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