Data Recovery Case File · Memory Cards · Drone / Monolith

The drone card that died with the originals aboard: chip-level recovery from a DJI microSD

The cruellest detail in this enquiry was that the customer could see his footage — in miniature. The microSD from his Mavic Air 2 had prompted for formatting, then stopped appearing in any PC at all; but with the drone powered on, the DJI app cheerfully displayed the gallery and let him save copies to his iPad. Copies which, as he'd correctly worked out, were only the app's low-quality cached versions. The 30–40GB of full-resolution DNG stills and MOV clips existed in exactly one place: a card no computer would acknowledge.

The enquiry

“The microSD from my drone prompted to format before use — I ignored it as I didn't want to lose the data — and now the card isn't detected at all. I can see the files through the DJI app and have downloaded them to my iPad, but those are only lower-quality temp files. The high-quality raw files — DNG images and MOV clips, roughly 30–40GB — need to come off the card itself.”

Reading the sequence

The card had told its story in the right order for once. The format prompt was the first stumble — the card's controller serving up something the PC couldn't parse — and refusing it was exactly right. The total disappearance that followed was the second and larger fact: the controller, the small brain that presents flash memory to the world as a tidy disk, had stopped presenting anything. The drone's app could still browse because it was reading its own cached previews, not the card — a distinction worth underlining for every pilot, because those thumbnails are reassurance, not footage. Crucially, a dead controller says nothing about the memory behind it. In the overwhelming majority of cards that die this way, the NAND — the silicon actually holding the DNGs — is sitting intact behind a failed receptionist.

Going in behind the controller

A microSD is a monolith — controller and NAND fused into a single sealed wafer, nothing to unplug, no chip to lift off a board. What it does have, hidden beneath its casing, are the manufacturer's own technological access points: test pads that allow the memory to be addressed directly, bypassing the dead controller entirely. The card was prepared and its pad layout established against the Visual NAND Reconstructor's pinout reference — every monolith family has its own map, and identifying the right one is half the craft — then wired for direct access and its NAND dumped in full via PC-3000 Flash and the Flash Extractor.

Raw NAND is not a filesystem; it's the controller's private filing system frozen mid-thought. Reconstruction ran the standard gauntlet in reverse: error correction across the dump, the controller's data-scrambling undone, page and block geometry established, and the translation layer rebuilt until the chaos resolved into the tidy logical disk the drone used to see. On that rebuilt image the exFAT volume came up cleanly, and the flight folders were extracted: the DNG stills verified by opening — full resolution, not thumbnails — and the MOV clips checked as playable end to end, long recordings reassembled across their fragments where the card's wear-levelling had scattered them.

Outcome

The complete card — every flight, full quality — delivered alongside the iPad's cached copies it comfortably replaced. Two habits to take from it, one general and one for pilots. General: refusing a format prompt costs nothing and preserves everything; this customer's refusal is why the reconstruction had a clean volume to rebuild. For pilots: offload after every flight day, and treat the app's gallery as a viewfinder, not a vault — the day a card dies, those previews are what you're left holding, and they don't grade, crop or print.

Our case files are drawn from genuine enquiries received by our laboratory over the past ten years, anonymised to protect client confidentiality. Each one describes the diagnostic and recovery procedure our engineers apply to that fault, using the equipment listed.