Data Recovery Case File · Cameras, Drones & Cards · A Real Overwrite, Measured
Software Installed Onto the Card Instead of the Device
His enquiry described an accident with an unusually clear cause. "My dad was downloading new satnav software and accidentally wrote it onto an SD card instead of onto the satnav. Would it be possible to retrieve image files from the card?" Most of the losses in this archive are apparent — files that look gone and are physically present behind a damaged index, where the honest answer is usually optimistic. This one is different, and it deserves the straight version. Writing software to a card is a genuine overwrite: new data was physically placed onto the card, and whatever it landed on is gone permanently. The question is not whether anything was lost but how much, and that is arithmetic rather than hope.
| Media | SD card holding photographs — navigation software downloaded to the card in error, physically writing new data across part of its capacity |
| Reported situation | Software written to the card rather than to the intended device · photographs previously held · extent of the written data relative to card capacity to be established · card not further used |
| Fault class | Partial physical overwrite — data outside the written footprint intact; overwritten regions unrecoverable by any means |
| Equipment used | Card imaged write-blocked (DeepSpar USB Stabilizer 10Gb) · overwrite footprint mapped on the image · format-aware carving of surviving regions · photographs validated by rendering and losses reported by position |
The decode: why this one is different, and how the arithmetic works
Why it is a real loss: most card cases involve a deletion, a format or a damaged filing structure, all of which remove the description of the files while leaving the files themselves physically present. That is why the honest answer is so often good news. Writing software to a card is not that. The download placed actual new data onto the card's memory, and physical replacement is the one operation that genuinely destroys — an overwritten region cannot be read back by any technique, at any price, by anyone. So this page cannot offer the usual reassurance, and it should not pretend to.
What the arithmetic is: the outcome is decided by two numbers. How much was written, and how large the card is. Navigation software with map data is not small — it is typically several gigabytes, and map updates for a full region can be considerably more. On a small card, that could be most of the capacity. On a large one, several gigabytes is a modest proportion and the majority of the photographs may sit outside it entirely. So the honest answer for anyone in this position is genuinely unknown until the card is examined, and it ranges from almost everything survived to very little did.
Why it is worth examining rather than assuming: two reasons for optimism within the honest framing. Writing tends to be contiguous — a download lands in a band rather than being scattered across the card — so the damage is usually concentrated rather than distributed, which leaves whole regions untouched. And a card is rarely full, so a good deal of what was written may have landed in space that held nothing.
What must not happen now: the card must not be used again for anything. That includes putting it into the satnav, which would write more; completing the software installation; and running recovery software that writes its output back to the card. Every further write extends the footprint into territory that currently still holds photographs.
What the deliverable should look like: a map rather than a percentage. The overwritten footprint is established on an image, the surviving photographs are carved from outside it, and the losses are reported by position — so he knows what came back and what did not, rather than receiving a vague estimate.
On the bench
The card was imaged write-blocked behind the DeepSpar USB Stabilizer 10Gb before anything else, freezing the position as of arrival. The overwrite footprint was mapped first on the image — establishing precisely which regions the software had claimed and which were untouched, so that expectations rested on measurement rather than hope. Format-aware carving then recovered the photographs from the surviving territory by their own internal signatures, since the filing structure describing them had been replaced. Every image was validated by rendering at full resolution, ordered by embedded capture date, and delivered with the lost regions reported by position.
The outcome
The overwrite mapped, the photographs outside it carved and validated at full resolution, and the losses reported by position. Recovery of deleted or overwritten data from memory cards and USB sticks is charged at a flat figure, payable upfront. The decode, for anyone who has written to the wrong device: this is a real overwrite rather than the usual apparent loss, so the regions the new data landed on are gone permanently and no technique changes that; the outcome is arithmetic — how much was written against how large the card is — and navigation software with maps is several gigabytes, which is most of a small card and a modest share of a large one; writing tends to be contiguous, so the damage is usually concentrated and whole regions survive; and every further write extends the footprint, so the card must not go into the device or be used again.
Something written to the wrong card or drive
Stop using it immediately — don't complete the installation, don't put the card into the device it was meant for, and don't run recovery software that saves its output back onto the same card. This is one of the few situations where data is genuinely destroyed rather than merely unlisted: new data was physically written, and whatever it landed on cannot be recovered by anyone. But the loss is usually partial. What decides it is how much was written against how large the card is, and downloads tend to land in a contiguous band rather than scattering, so whole regions typically survive untouched. Expect an honest answer that ranges widely until the card has been examined, and ask for the result as a map of what survived and what didn't, by position, rather than as a percentage estimate offered in advance.
Take it out and leave it out — call Glasgow Data Recovery on 0141 404 0294; imaged write-blocked, the overwrite footprint mapped, everything outside it carved and validated.
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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.