Genuino 101 not recognized after sketch upload

I have two Genuino 101 boards and running Ubuntu 16.04. I upload the same sketch file to both boards. For one board everything works fine, the board is recognized by the PC and performs as expected. However, the second board is not even recognized by the PC. That is, /dev/ttyACM0 does not appear.

I have tried hitting master reset and unplugging/plugging the USB back in. I've tried uploading other sketch files (e.g. Blink) and they work fine. It is only seems to be this particular sketch on this particular board that is causing problems.

The sketch file is a bit large to post, but I essentially modified this file by taking out all of the Port manipulation calls in order to make it compatable with the Intel Curie.

It does sound like a possible bad board.

Are they both fully up to date firmware wise etc.

Will presume you disconnected everything from each board prior to upload etc for testing.

Are you using the same PC and IDE for both boards ?

Not a Linux user so don't know if it is supposed to show on a different port like they do under Windows ?

BTW the sketch looks a little like the FIRMATA ones...Maybe take a look at those the ones I have tried compile fine for the 101