The cable within the Clock Spring situated in the steering wheel can delimitate and become entangled within the assembly. This can cause a short circuit which can activate the horn or lights without warning and in extreme cases the driver's airbag.
The battery harness may not be sufficiently secured. There is a chance if not noticed during servicing that the insulation of the harness could chaff and expose the wiring. This could then generate sparks and excessive heat within the engine bay.