There are obviously some doubts concerning the explanations in this story, new newspaper article claims
Quote (Google translate): Contrary to what government officials have suggested in initial responses, security agencies can not yet conclusively state that it was all about technical failure. There are apparently indications from the friendly foreign countries. Experts had been skeptical as soon as the incident became known that both the radio and at the same time the device for discharging kerosene had failed
(go to tagesspiegel.de-zwischenfall-vor-g20-gipfel)