I had similar problems, glitches, mini hits on a model. But only when inverted.

Couldn't find the answer, kept on flying then lost it during a low inverted. Totalled.

Only after doing a complete wreakage PM did i see that the plastic wire coating had worn away on the battery lead and was shorting out as it moved from upright to inverted.

Increadble to think a loose wire will wear down over time. 

Well they do.