Prohibitory sign on boot, replaced drive to no avail

[v-squared]

Hey everyone, long time lurker who is ever so greatful of this forum. Saved me a bunch of frustration over the years.

I've got one I haven't been able to find an answer to. My girlfriend was browsing on her 2011 MacBook Pro 13 inch two days ago, and she said it was running very slow and getting the spinning pinwheel a lot. She had similar symptoms in the summer, and so we swapped out her drive with a Samsung 850 SSD. Machine ran great.

Fast forward to this week, and it starts doing it really badly. I had a look and decided to restart. Upon restart, the boot screen grey progress bar gets a little past halfway, then goes to the prohibitory sign. Try and boot again, no luck.

Boot into disk utility and run first aid, get a few errors on the disk. Try and repair the disk, but it says it can't. Apologies that I don't remember the exact wording of the messages.

I attach the MacBook to my iMac via firewire and target disk mode to see if I can recover her data, and it loads no issue. I grab everything off the drive suspecting it is failing, and order a new 256 gb 850 Pro.

I go ahead and install MacOS Sierra on the new SSD using my iMac and a hard drive adaptor cable. Put the new drive in and attempt to boot up to the exact same results, progress bar gets just past half and then Prohibitory sign.

Now I'm thinking maybe I have to install the OS with it in the laptop, so I try to boot to the USB with the OS install on it, and I get the same result, the prohibitory sign.

Lastly, I've reset the PRAM and SMC just in case. I'm out of options and ideas at this point. Sorry for the long winded post but I wanted to be as thorough as I can.

UPDATE:

I was able to get it into Disk Utility on boot. After holding CMD+R on startup, it loaded to the apple logo, then to the Prohibitory sign. I left it sitting at that point, and it eventually booted to Recovery. However, now in Recovery, it is taking an incredibly long time to do anything. I loaded Disk Utility and it took nearly 5 minutes to see the drive.

 

[prisstratton]

Okay, I have a couple of other ideas for you to try.

1. Plug your girlfriends SSD into your Mac using an enclosure or USB/SATA connector and option boot to the drive. If it boots successfully this will tell you that it is okay and therefore not the drive that is at fault.

2. A couple of years ago I was installing a new SSD and ran into the prohibitory sign. At the time all I had to do once I booted into the restore partition was to tell the OS that this was my startup drive and it was fixed.

3. Maybe it is the SATA cable in the MBP. I thought 2012 models were more prone to this, but you never know. The fix is not supposed to be too difficult, guide here:

https://www.ifixit.com/Guide/MacBoo...+Early+2011+Hard+Drive+Cable+Replacement/5120

Based on your explanation of events, i.e., half assed communication with the drive I wonder if this might be the root of your problem.

Please give these ideas a try and report back your results.

I hope it helps, good luck.

 

[Fishrrman]

If the internal drive WILL NOT boot while mounted internally
...but...
If it WILL boot and run fine when mounted externally....
...then...
It points to a failing internal SATA ribbon cable.

If you've taken the drive OUT, then you already are familiar with working inside the MacBook.
Just get ahold of a new ribbon cable.
Try ifixit.com for the part number (they sell the cables, as well).
Or.. go online elsewhere to find it.