Excessive dust can cause overheating, which can cause a variety of issues, but it would be extremely rare, unless it was some kind of METALLIC dust, for it to cause a short. More likely is something had a poor connection due to not being seated well in the beginning when it was first built, and over time vibration or minor impacts from movement of the case caused something to break it's connected and when you reconnected or fiddled around inside the case you managed to reestablish the connection. I'd give everything with a connection a good once over to look for any areas that look like they might be even slightly darkened or melted from the increased resistance of a poor contact and reseat each connection firmly just to be sure.
Either way, glad you got it sorted out.