When playing with some eMMC from vendors like LG, you have to deal with the encryption root keys being also zapped on flashing recovery and cache, that is why flashing back the factory images didn't help. Always keep handy a full eMMC raw image of the original device, which if you flash back - everything, including the encrypted user data partition - you get the original device state. Flashing just different parts might generate new encryption root keys on boot, which will fail to open a previously encrypted user partition.
Fully agree and this might be the case. I'm not sure now about K8 but i'm 100% sure K10 is not encrypted by default. K8 was released a bit later and from what i see it started with 6.0 (instead of 5.1.1 like K10) so maybe this one was and force flashing TWRP generated new encryption key as you say. I might try making some more tests next time out of curiosity.
Faulty eMMC exist, but they are rare. Let's make some maths with presumptions
- if 0,1% of the phones got faulty eMMC
- if 1 out of 10.000 sold devices are involved in forensic cases
- split by vendors, implementations, eMMC versions and hardware revisionsThere are pretty big chances that 1 out of 1.000.000 devices will have a faulty eMMC prior to a forensic case anyway.I might say low chances, but proven to exist now and then )
I would really welcome if any mobile vendor could correct my presumption numbers…
Thinking globally, you're most likely right with those numbers. Still, for some models stats are probably a bit worse (take Galaxy S3 and Note 1 and Note 2). I'm less forensic oriented, more repair and data recovery focused and if it comes to repairs, there are weeks when i have 3-4 devices in store with faulty eMMC. Last week it was K10, today it was HTC One M9u (no download mode, unable to flash anything including HOSD, known issue) - if i recall correctly it's 3rd or 4th M9u with that issue in past 6 months that i got to fix. I've had like 30-40 Galaxy S3, probably same amount of Note 2. Countless LG devices from series i mentioned in my earlier post. There was a week when i got 3 i9195 with dead eMMCs from 3 different customers etc. It was also a popular problem in Lumia phones, mainly 520 and 625 where eMMC switched to read-only mode and this resulted in "unable to find a bootable option" error. There are tons of posts on gsmhosting and xda-developers forums regarding issues like this in various devices and one of the reasons why boxes like easy-jtag, riff, medusa, emmc pro, ufi etc exists 😉
You're not seeing it as much in forensics type jobs and i'm not saying this is the case here. In fact, i'm 99% sure it is not.