Warning: SD card might fall off on Rev4 boards!
Since it happened twice already, this is probably worth a warning...
Today Jeff sent me these two pictures, it's quite clear what happened.
The SD card came off, without any force. A similar thing happened a few months ago with a board that I soldered and sent to Germany. It was broken when it arrived.
It looks like the SD card solder pads are not very strong. If some force is applied (or maybe even hardly any force) they can break from the board, resulting in a more or less useless motherboard.
Probably, you can prevent this by making sure that the through-hole connectors of the SD card (on the sides) are soldered very well.
I appear to have been able to hack this back together without too much difficulty, I am posting some images here to help anyone that ends up in the same situation.
The pads for the SD card socket were pretty well ripped off of the board and I wanted avoid any further damage to the board so I decided to run ribbon cable directly to the MBED socket. The double row socket ended up making this quite easy to do. Using the socket that had come off the board, I soldered the ribbon cable onto the socket directly then used a row of header pins that I had on hand to make a plug to plug into the MBED socket. I followed the schematics from the GIT repo to get the pin-out for the board/MBED side along with the pinout information for the SD Card (See attached image). The SD Card pin numbers are a little strange with pin 9 being on the same end as pin 1 so it is important to ensure you get the correct pins if you are following along with the schematic. I was able to use the ground pin on the MBED socket for ground however for the 3v3 I soldered directly onto the board at the most convenient point I could find.
I have not yet decided how I am going to mount the socket so I reinforced the connection with some hot glue. Not the prettiest but it was necessary to maintain structural integrity. One additional word of caution on the SD Card Socket end: Be careful to mind the heat going into the pin when soldering wires onto the pins. There is very little plastic holding the contact in place and it is very easy to have the contact come loose if the plastic gets too soft.
Since I am just getting started with figuring this all out, I am unsure if I will have reason to insert and remove the SD card regularly but with the thought that this may be necessary, I am considering 3d printing a panel mount for the SD Card socket. If I go this direction, having the SD Card detached from the board and on a ribbon cable may end up being a benefit.
I have now been able to run the test firmware and it appears as though everything is working. Next steps will be to get the cabling set up to hook it up directly in my K40 and go from there. If anyone has any questions on how I hooked up the SD Card socket, feel free to ask. I can provide more pictures as well. If I end up making a panel mount for the SD Card socket, I will post the information for that as well.