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PostPosted: Wed Oct 19, 2016 3:36 pm 
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Trying to fix a Macbook Pro that apparently was 'fixed' somewhere by replacing the data cable. It now has a different issue and I've been asked to fix the new problem that the other place caused. I should mention initial problem was the question mark and other boot issues that probably was related to a bad data cable (I'm guessing). However after that cable was replaced the machine now does this.....Upon powering, up the chime sounds the screen flashes bright white for just a second and then remains black.

I reset pram with no change. Have not looked internally yet.

Any Ideas?


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PostPosted: Wed Oct 19, 2016 4:02 pm 
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I would try resetting the SMC, possibly a complete motherboard reset (remove battery from board, press power button, reconnect battery, reinstall cover, open laptop, connect to power brick).

It could be trying to restore from a corrupt hibernation. At least I think that's whats happening when it does this.

I would try holding down option on that first boot to interrupt the boot process and bring up system picker.


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PostPosted: Thu Oct 20, 2016 5:59 am 
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MonkeyBoy wrote:
I would try resetting the SMC, possibly a complete motherboard reset (remove battery from board, press power button, reconnect battery, reinstall cover, open laptop, connect to power brick).

It could be trying to restore from a corrupt hibernation. At least I think that's whats happening when it does this.

I would try holding down option on that first boot to interrupt the boot process and bring up system picker.

This had a positive effect MonkeyBoy and got me back to the desktop after a couple of attempts by the laptop to reinstall or change the password or in some other way recover from a presumed meltdown. I selected restart rather than alter anything and on restart was presented very quickly with a login screen (white background). I logged in and it went through the boot process and at the end of that process I was presented with the more typical login screen with which I am familiar (background is a veiled opaque view of the desktop picture). So that's 2 logins in one boot. Since that occurred, restarting or starting from off presents a login dialog very early in the process (white background) but only once and results in a seemingly proper boot to the desktop.

I have not seen this behavior before. Might this be a function of 'File Vault'???

BTW, this is past due, but I want to thank you, sincerely and with much appreciation, for the number of times you have helped me solve computer related problems. I started to count the threads in which you specifically have assisted me but there were too many to proceed. It's been multiple machines and varied situations from Macs to PC's, even an occasional hackintosh issue. I want you to know that in that same spirit I try to pay it forward and help others when I can. When I am posting questions here, it is usually when I am working on a computer owned by friends or family members or friends of my kids. I never accept any form of payment for helping them and that is one of the ways I try and spread the helping spirit you (and several others here) have given so freely.


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PostPosted: Thu Oct 20, 2016 9:42 am 
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Most of the knowledge I express here has been gained by working on systems owned by students, friends, coworkers, and family. If I didn't have an IT job I don't know where I'd get that kind of stimulating input and rewarding output.

Ohhhhh, FileVault. I have limited experience with it but my understanding of current FileVault (full disk encryption) is that the boot process goes as follows:
1) Boot from recovery partition
2) Prompt user for password to unlock encrypted partition
3) Mount encrypted partition using password
4) Boot from encrypted partition

In the case of a system going into hibernation mode, that hibernation file should be stored on the encrypted partition, so it should prompt you for a password before restoring.

Since it wasn't prompting you for a password there was a problem very early in the boot process. When normal sleep happens it basically leaves the encrypted disk unlocked and mounted.

By resetting the motherboard you forced it to go through the normal 1-2-3-4 boot process because it had no crutches to fall back on for a faster boot.


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PostPosted: Thu Oct 20, 2016 11:15 am 
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MonkeyBoy wrote:
Most of the knowledge I express here has been gained by working on systems owned by students, friends, coworkers, and family. If I didn't have an IT job I don't know where I'd get that kind of stimulating input and rewarding output.

Ohhhhh, FileVault. I have limited experience with it but my understanding of current FileVault (full disk encryption) is that the boot process goes as follows:
1) Boot from recovery partition
2) Prompt user for password to unlock encrypted partition
3) Mount encrypted partition using password
4) Boot from encrypted partition

In the case of a system going into hibernation mode, that hibernation file should be stored on the encrypted partition, so it should prompt you for a password before restoring.

Since it wasn't prompting you for a password there was a problem very early in the boot process. When normal sleep happens it basically leaves the encrypted disk unlocked and mounted.

By resetting the motherboard you forced it to go through the normal 1-2-3-4 boot process because it had no crutches to fall back on for a faster boot.

That sounds spot on. Everything working well.


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PostPosted: Thu Oct 20, 2016 12:07 pm 
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We are very fortunate to have MB here. :welcome: :coffee:


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PostPosted: Thu Oct 20, 2016 1:32 pm 
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BD you have no idea how much stuff I've read that was written by you I simply had no idea about before I read it.

My only hope is that when I do finally encounter it that I can pull it out of long term memory intact without making a fool of myself :lol:

Edit: Me fail English? That unpossible.


Last edited by MonkeyBoy on Thu Oct 20, 2016 5:43 pm, edited 1 time in total.

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PostPosted: Thu Oct 20, 2016 4:18 pm 
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Ah yes, I've forgotten far more than I know.


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PostPosted: Thu Oct 20, 2016 11:52 pm 
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BDAqua wrote:
We are very fortunate to have MB here. :welcome: :coffee:

Hear, hear. I have no idea how he packs so much into his brain. Thank you MB.
Though I had no interest in the topic, I clicked on this because I saw you (MB) had responded and I always like to read what you say. :)


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PostPosted: Fri Oct 21, 2016 2:25 am 
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:)


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PostPosted: Fri Oct 21, 2016 3:17 pm 
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I forget something every day, whether I need to or not.

And as always, let my reiterate my appreciation of BD for all he's done and everyone he's helped for so many years.

- Anonymous


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PostPosted: Fri Oct 21, 2016 7:11 pm 
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Anonymous wrote:
I forget something every day, whether I need to or not.

And as always, let my reiterate my appreciation of BD for all he's done and everyone he's helped for so many years.

- Anonymous

Here here! :) BD saved my bacon many times ... going way back to the days over at XLR8YourMac. He walked me back from the cliff many times when SCSI issues had me ready to leap.


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PostPosted: Fri Oct 21, 2016 7:50 pm 
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:)


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PostPosted: Mon Oct 24, 2016 3:56 pm 
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I don't know what it is, but lately I've been helping people get FileVault turned off after they somehow turned it on by mistake. Its been a half dozen people or so over the past couple months, which is why my memory of it is fresh. If people stop encrypting their disk or stop bringing it to me after they encrypt their disk (some folks feel embarrassed, though I'm generally regarded as the nice IT guy everyone likes to bring stuff to), I may start forgetting about FileVault again.

I kind of look at FileVault as being of limited use to me simply because I boot into multiple OSes and frequently need to rummage around in the other partitions for data. With FV enabled the other OSes won't be able to read Macintosh HD. Which is part of the appeal, I know, but its just not appealing to me.


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