Q: How to read from 256GB PCIe-based flash storage

OWC (macsales.com) and perhaps others may have a Thunderbolt enclosure that will work with the proprietary connector on the SSD. Before you resort to that, make sure the computer won't start in target disk mode (T key down at startup.)

Try Target Disk mode:

http://support.apple.com/kb/HT1661

Unless you can find a compatible enclosure, the only other alternative is to swap the SSD into another Mac and then copy the data.  Not a easy and clean proposition.

Ciao.

Ciao.

Stinks when you lose your data, I feel for you. The only silver lining of this disaster is to take the lesson to make sure you have at least one backup in the future. Apple made Timemachine very easy to use and setup and practically foolproof.

How did you determine that it is a logic board failure?

Starting from an external USB storage device (Intel-based Macs)

OWC has their slimline, external Envoy enclosure for receiving the PCIe storage card from a MacBook Pro (2012 - Jan. 2013) models. In red ink, they emphasize it is not to be used for Fall 2013 or later MBP technology — so that solution is out.

Here is an iFixit guide on how to remove the PCie storage card from a 2014 MacBook Pro, in case you need to go there.

Out of town right now, so don't have access to a traditional SATA machine to test if Target Disk Mode still works with new 2014 PCIe machines.

A 11,2 MBP is late 2013 rMBP - How to identify MacBook Pro models.

Vikings guide is for 2014, you may also want to look at https://www.ifixit.com/Guide/MacBook+Pro+15-Inch+Retina+Display+Late+2013+SSD+Re placement/23431

This may help http://www.amazon.co.uk/mSATA-PCI-E-Convertor-Enclosure-Adapter/dp/B00BTH7DEY