Fortinet FortiGate-100D NAND Flash Replacement

I have an old Fortigate 100D with a failed disk drive probably from getting thrashed with logs and is not booting. When trying to boot from the recovery procedures it give a warning “Warning get data disk fail.” then it faults and crashes.

This seems to be a very early unit as the main spec sheet mentions 32Gb, you can see the space for the extra 16Gb on this board.

naked glory!! where we are going we don’t need a warranty

Flash Drive Part

This is an early revision of the board so the second slot has not been populated

Boot up, boot device capacity: 15272 MBytes (2x chips of 64Gbits). So there is a chip on the underside along with the controller,

MT29F64G08CBAAA NAND Flash Memory

Density: 64Gbit

It is a pair of MT29F64G08CBAAA NAND Flash Memory which is an 8Gb part with a Phison PS2251-61-5 USB 2.0 Flash Controller

Phison PS2251-61-5 USB 2.0 Flash Controller


Masking out the board with Polyimide film to protect from excessive heat.
NAND Removed and board Cleaned.

Booting the unit without the NAND it just sits around “Boot up, boot”

Installing to external USB thumb drive

As it turns out the internal disk is just a cheap USB Thumb drive soldered directly onto the board. strange design choice.

Removing the JUSB2 jumpers and using an external USB thumb drive you can run through the TFTP boot recovery process and reinstall onto the external disk.


Going Forward

Instead of using recovered parts for a donor SSD drive I had in a pile of junk I might just order some new NAND chips from mouser.


Anyway with the removed NAND I transplanted it to the donor board for testing, but the flash controller would probably just cover up any failures.

got a lifted N/C pad there but we all cant be prefect.

Might have to order a FlashcatUSB Mach¹ for fun and profit see how bad these chips got.