John-Del wrote on 6/22/2017 4:15 PM:
On Thursday, June 22, 2017 at 3:48:13 PM UTC-4, rickman wrote:
frank wrote on 6/22/2017 7:47 AM:
Hi,
I already know the answer but we never know if anyone out there can make
miracles
I've been given a dead USB drive, in my linux laptop is identified as usb
storage device but it fails to read (probably) the capacity and the usb stack
keeps on resetting the device.
It's not possible to open it, looks like a small solid plastick stick with
metal tabs embedded on one side. It's just a bit longer than the typical
usb slot.
I tried heating and freezing it, just in case it was some temperature
sensitive fault, but behaviour never changed.
I don't think there's a way to expose the actual NAND-flash chip and read
it separately, but I'm asking the expert here
Did anyone ever found a way to open (or otherwise read) these little
data killer devices?

Just to be sure, you are talking about a USB Flash drive, right? I've yet
to find one I couldn't open. It would cost them extra money to make them
hard to open, solid plastic.


A good buddy of mine had some data and pictures on a flash drive that he could no longer read on his computer or any recovery software. So I opened it up looking for bad solder on the chip or a problem with the USB connector. Sure, the plastic outer case opened up easily enough but there was nothing inside. That's right, nothing.. Other than a two piece outer plastic case, the drive was a USB connector soldered to a multi-layer board with no external components on it. Whatever it used for a chip was embedded inside the PC layer.

Was there a black blob on the board? That would be epoxy covering the die
mounted to the board. I see that on high volume, low cost products which
only need one or two chips. Actually mounting chips inside the PCB is not
something I've ever seen or heard of before. Not saying it's impossible,
but it would be done for low cost and I don't think it would be any cheaper
than the epoxy blob and in fact may be slightly more expensive.


The lesson here is that Flash chips are not terribly reliable for long term
storage. Anything on a Flash drive should be backed up on another Flash
drive or your computer hard drive or both. Backup, backup, backup.

I have a library of .bin files for TV mainboards on 4 thumb drives as well as three PCs I own and several PC from others in the business. Too many years removing soldered-in eeproms and reading them to lose them to a balky flash drive.

Flash memory inherently wears out. It also has issues being made. To deal
with both problems the chips are made with extra capacity and error
correcting codes are used to find and correct errors. When a sector is
found to have errors, the data is copied over to a spare block and the old
one is marked as bad. The problem comes when there are too many errors to
read the data on a failing block or when all the spare blocks are used.
This makes SSD storage susceptible to sudden failure.

--

Rick C