Wipe M1 drive before selling on non-bootable machine

[johnquid]

Hi all, I have an M1 MacBook Pro whose display got fried after a drink got spilled on it (it boots up, and you can see a shadow of the Apple logo and progress bar, but it just gets stuck there). I took it into a couple shops and they and got quoted around $1k for repairs.

I ended up just buying a new one and want to sell the damaged one on eBay, but I want to wipe the drive and now that the drives aren't removable I'm a bit lost on how to do that! I don't recall if FileVault was enabled and I've tried attaching an external monitor to it, but that doesn't seem to be working either.

Is there something I'm missing, or is this just not possible now?

 

[okkibs]

You can use a flashlight to shine on the internal screen, if only the backlight is fried and you can see the Apple logo it might be usable, though I doubt it from how you described it. You'd need recovery mode, so hold the power button when turning on until a menu appears where you can go to recovery. You can wipe it there if it boots that.

If it doesn't boot recovery there is no way to wipe it. You could obviously take out the logic board that contains your data and sell the Mac without it, for spare parts, like the display. Although you'd have to sell it as defective since you don't know what's damaged.

Do you know if this Mac was logged into your Apple account? If you are unsure you can check if it appears in your list of devices from another Apple device. And do you know if Find My is enabled?

And finally, do you know if all your accounts on the Mac had a password set that isn't too simple and can't be guessed?

Because if all accounts have a solid password set and it's connected to iCloud, it does not matter* if Filevault is turned off, because without either the password of your Mac account or you Apple account, the Mac only allows to factory reset.

*there is a difference:

Spoiler

With Filevault off the data is still encrypted on the flash storage that sits on the logic board, but the recovery can access that data directly and just locks you out without your password. If there was some exploit that could trick the recovery into skipping that protection, since it can access the data, it would then be possible to copy it off the Mac. If Filevault were on, such an exploit could not work because Filevault adds one additional encryption that the recovery can never skip.

 

[Fishrrman]

Try connecting an external display, see what you get that way.

Do you have a brick-n-mortar Apple Store anywhere near? They might help.

If you can't get the data "off the drive", and you're concerned about what's on it, then I'm thinking removing the logic board + sledgehammer might be the only solution... (sigh)

 

[johnquid]

You can use a flashlight to shine on the internal screen, if only the backlight is fried and you can see the Apple logo it might be usable, though I doubt it from how you described it. You'd need recovery mode, so hold the power button when turning on until a menu appears where you can go to recovery. You can wipe it there if it boots that.

This was a good idea, but didn't work, unfortunately.

Do you know if this Mac was logged into your Apple account? If you are unsure you can check if it appears in your list of devices from another Apple device. And do you know if Find My is enabled?

Yes and yes, I can see the MacBook in my list of devices and Find My is enabled on it (though, it's showing "No location found" even with being on right now, I guess it has to be logged in)

And finally, do you know if all your accounts on the Mac had a password set that isn't too simple and can't be guessed?

Ah yes, there is a good password for iCloud and the Mac that couldn't be guessed and this is a good point. I suppose they'd have the same problem I have in that they'd have to break the login to access the data since they can't just add the drive to another computer.


Thanks okkibs!

 

[johnquid]

Try connecting an external display, see what you get that way.

Do you have a brick-n-mortar Apple Store anywhere near? They might help.

If you can't get the data "off the drive", and you're concerned about what's on it, then I'm thinking removing the logic board + sledgehammer might be the only solution... (sigh)

Yeah I did try and external display, but that didn't work

Yes there are a couple brick-n-mortar stores nearby, I can try them as well, I wanted to try posting here first try in case there was a solution I could do myself.

 

[okkibs]

I think you can't sell the Mac with the logic board anyways because it is connected to FindMy, i.e. activation lock is active. Nobody accepts activation locked device as it basically means the logic board is bricked. Though perhaps erasing it online and then removing it from your account might disable the lock, but I'd have to try it and I don't have a spare device for that right now.

I guess it has to be logged in

Try locking it and erasing it over iCloud. It might not get a location but if it connects Wifi it will immediately get the wipe instruction from Apple's servers. With how damaged it is it's unlikely but you don't lose anything by trying either.

I suppose they'd have the same problem I have in that they'd have to break the login to access the data since they can't just add the drive to another computer.

Yes - and especially if you lock and erase it over iCloud, you can make sure that as soon as someone fixes it and tries to start it, it will erase. But the downside is that you won't get any money for an activation locked device... kind of a catch 22.

If they try to gain access to your data with Filevault off they'll be asked to login to your Apple account. And since they can't, recovery should not allow to reset the password. Unfortunately whilst that is how it should work, I can't guarantee it, even other than a deliberate exploit, a simple bug could allow for skipping that somehow.

 

[johnquid]

I think you can't sell the Mac with the logic board anyways because it is connected to FindMy, i.e. activation lock is active. Nobody accepts activation locked device as it basically means the logic board is bricked.

Ah yes, good point, I didn't think of that.

Try locking it and erasing it over iCloud. It might not get a location but if it connects Wifi it will immediately get the wipe instruction from Apple's servers. With how damaged it is it's unlikely but you don't lose anything by trying either.

Yup I can give this a shot, I've checked my wireless access point to see if it was connecting or not earlier and it wasn't, but agreed it wouldn't hurt at this point.

If they try to gain access to your data with Filevault off they'll be asked to login to your Apple account. And since they can't, recovery should not allow to reset the password. Unfortunately whilst that is how it should work, I can't guarantee it, even other than a deliberate exploit, a simple bug could allow for skipping that somehow.

Yeah agreed on can't be sure given the person would have physical access and thanks for pointing that out.

Sounds like my best solution is to take out the logic board and sell it as defective. It's a shame to have to waste a potentially good logic board, but guess this is the downside to having the disk soldered to it now

Really appreciate your thoughts/help here okkibs!

 

[okkibs]

Sure. Last idea, you could send the device to rossman repair group in Texas, maybe they find a cheap fix, then it's worth more for a sale and you can get the data removed (or keep using it).

Or if you are taking it apart anyways, you can submerge the logic board in 99% isopropyl alcohol (cheap on amazon), gently clean every spot with a toothbrush, then let alcohol evaporate for 24 hours and assemble again. That will get rid of residue from fluids and if no permanent damage was done it should fix the issue altogether. Remove the heat sink beforehand as it prevents access to all components for cleaning. See attachment, taken from ifixit.