In the building events I have participated in at nationals I have found that the vast majority of the event supervisors are very knowledgeable in the events and while quite strict, the event supervisors generally err on the side of the students if they are unsure. I dont think they would DQ someone without good reason.
More importantly, they should've been quite clear why you had been disqualified. (Note: I consider DQ to be "do not pass go, do not collect $200" type offenses.) (Knowingly) cheating would get you a DQ, whereas having a device that didn't meet a spec would merely be a technical offense, and get you ranked below other teams who were in spec.
If you're DQ'ed, your coaches can file a protest to the arbitration board. If we don't explicitly state why you were disqualified, it almost always results in an overturned DQ.
For the record, as a event supervisor, I'm currently 13-1 in arbitrations, and the one we lost, we realized we had screwed up before the arbitration board made a decision. We ended up letting the team run their device again to attempt to gain maximum points, which they felt was a fair compromise. We do our best to keep things as fair as possible, while resolving problems without arbitration as a rule. Being that many judges are now also SO alumni, we understand how much work you've put into your events- and we want to honor that as much as possible because it's what we'd want for ourselves.
The Evangelist Matthew Inspired by an Angel (1661) by Rembrandt van Rijn
Oil on canvas, 96 x 81 cm, Louvre