The ignition does not have to be "turned over to run" to record and ignition cycle. While you may have used a technique to backpower the ACM to do the download, you haven't mentioned why you had to backpower in the first place. Was the key in the vehicle, was the battery disconnected, were there electrical problems with the vehicle at the scene of the collision before the battery was cut that might have produced a bunch of voltage fluctuations, did someone else turn the vehicle on/off 133 times before you applied power to the ACM, etc.?
I had a crash a couple years ago that I worked on where one of the vehicles was involved in a prior collision, and then purchased by someone who attempted to rebuild the vehicle a bit at a time. He started with repair that were just sufficient for him to get the vehicle back on the road and inspected, which included replacing the driver and passenger airbags. He did not replace the ACM, even though the airbag light would not go off, as the vehicle was still driveable and it the light didn't really bother him all that much. When he was involved in this frontal crash the airbags he replaced actually deployed, however, the data I retrieved from the ACM didn't seem to make any sense when compared to the witness statements and the scene evidence. Since the ACM was not replaced after the first crash and the data on the ACM was locked because the airbags had deployed in the first crash, the data I retrieved was from the initial crash, not the one I was investigating.
Even though the speed and delta-v data was the first sign of a problem in my case, when I looked a the data more carefully I observed that the ignition cycles at download were nowhere close to the "at event" ignition cycles. In your case, you would have to have an airbag deployment that occurred relatively recently in the history of the vehicle in order to be similar to my case. I would start with a vehicle history report and see if the vehicle has been involved in any other crashes where the airbag deployed. If there is no history of a prior crash with an airbag deployment you are that much closer to relating the data to the crash you are investigating.