Signature failure, controller corruption, firmware corruption — three names that usually describe the same underlying event on an 860 EVO. The V-NAND is generally intact; what has failed is the layer that knows how to read it.
An 860 EVO stores your data across V-NAND dies and keeps a translation layer describing where each block actually sits. Lose that layer and the drive still holds everything — it simply no longer knows how to present it.
These three terms come up interchangeably, and in practice they usually describe stages of the same failure. The 860 EVO’s MJX controller loads its operating firmware from a reserved service area on the NAND at power-up, and it verifies that firmware before running it. Signature failure is that check failing — the firmware image no longer matches what the controller expects, so it refuses to load. Firmware corruption is the cause: one or more modules in the service area have become invalid. Controller corruption is the symptom you see, because a controller with no valid firmware cannot present a usable drive.
What follows is characteristic. The drive may vanish from the BIOS entirely, or appear with a blank model string, or enumerate at an absurd capacity — 0 MB, 8 MB, or a few hundred megabytes rather than its real size. Some units enter a vendor safe mode that responds to identification but refuses all reads.
The commonest trigger is losing power mid-write. The controller maintains mapping tables constantly, and an unexpected cut can leave a service-area module half-written and failing its checksum on the next boot. Ageing plays a part too: the reserved blocks holding firmware wear like any other flash, and once the controller can no longer read a clean copy of a module it has nowhere to fall back to.
The third cause is self-inflicted — a firmware update that stalls, or one applied to a drive that was already unstable. Samsung Magician updates rewrite the service area, and an update interrupted partway leaves precisely the condition described above. This is why a firmware flash is the worst possible response to a drive that has already started misbehaving.
The work is to bypass the failed firmware rather than repair the drive for reuse. The controller is put into its vendor technical mode, which allows the service area to be read directly, and the surviving firmware modules and translation tables are extracted from there. Where a module is unreadable, an equivalent from a matching donor of the same capacity and revision can supply what is missing, so the controller can be brought up far enough to address the flash.
With the drive responding, it is imaged read-only, and the file system rebuilt from that image rather than from the drive itself. Where the controller cannot be recovered at all, the alternative is reading the V-NAND directly — but that produces raw flash that still has to be de-interleaved, corrected for ECC, and unscrambled according to the controller’s own arrangement before it means anything. That is slow, specialist work and not every case justifies it.
The first is encryption. The 860 EVO supports hardware encryption, and if Class 0 or TCG Opal was enabled — or BitLocker was using it — the data is only readable with the correct credentials. We do not break encryption and no recovery firm can; without the key or password, a perfect image yields nothing usable. Check for a BitLocker recovery key in your Microsoft account before assuming the worst.
The second is TRIM. If the files you want were deleted from a working drive, TRIM has almost certainly already erased the underlying blocks and there is nothing to recover. That is a genuinely different situation from the one on this page: here the drive has failed while holding your data, which is the recoverable case. A free 48-hour diagnostic establishes which of the two you are actually dealing with before anything is quoted.
SSD and NVMe recovery, including the 860 EVO, is from £300 +VAT. Every job opens with a free 48-hour diagnostic and a written quote, and most are handled on a no fix, no fee basis — where controller-level physical work is required we take a 50% deposit, with the balance payable only if the recovery succeeds. The drive can be dropped at John Eccles House on the Oxford Science Park or sent by insured post; send the bare drive rather than the whole machine. If the SSD is soldered to a laptop board rather than removable, tell us the model and we will say straight away whether it is something we can take on.
It means the controller has checked the firmware held in the drive’s reserved service area and found it no longer matches what it expects, so it refuses to load it. The drive then presents as missing, blank, or at a nonsensical capacity. Your data is not what has failed — the code that reads it is.
Almost always, yes. Controller and firmware faults stop the drive presenting itself, but the V-NAND still holds the data. Recovery means reaching the flash by another route — vendor technical mode and service-area repair first, or reading the NAND directly if the controller cannot be revived at all.
No. A firmware update rewrites the exact region that is already damaged, and an update that stalls on an unstable drive can make it permanently unreadable. If the data matters, stop and have it diagnosed before anything writes to the drive.
Only with the credentials. The 860 EVO supports Class 0 and TCG Opal encryption, and BitLocker may be using it; without the password or recovery key the data cannot be decrypted by us or by anyone. Check your Microsoft account or domain records for the recovery key first.
SSD and NVMe recovery is from £300 plus VAT, fixed in a written quote after a free 48-hour diagnostic. Most jobs are no fix, no fee; controller-level physical work carries a 50% deposit with the balance due only on success.