When you play a sequence on the OT’s MIDI sequencer, do you get a single-pixel dot appearing in the upper-left corner the OT LED screen (which indicates that MIDI information is being sent)?
There is a slight possibility that the Project data has been corrupted:
http://www.elektronauts.com/t/ot-midi-out-port/7375
What happens if you start a new Project on the OT and try to sequence?