DellInspiron17-3721

The Problem¶

I have got a Dell Inspiron 17 3721 laptop which does not turn-on anymore. Only a single beep error code, nothing on the screen. Beep code 1 means: "Motherboard: BIOS ROM Failure".

Source: https://www.dell.com/support/kbdoc/en-us/000132041/understanding-beep-codes-on-a-dell-notebook-pc#inspiron-laptop

The Idea¶

A corrupt BIOS ROM, how-to repair? The BIOS chips are SPI based EEPROMs of type SOIC8, which are most likely became corrupted somehow. Looking around at bios-fix.com there are two chips which needs to be flashed.

Digging through my pile of hardware a have a buspirate v3 which I could use to re-program the BIOS chips.

• https://maidavale.org/blog/flashing-the-bus-pirate/
• https://dangerousprototypes.com/docs/Bus_Pirate#Firmware_upgrades
• tooling found at https://github.com/therealdreg/buzzpirat

• I need to be able to access the chips. The Owner manual is a good source for opening the laptop.
• De-soldering the BIOS.
• A SOIC8 test clip is required with good quality cables. The guide at dangerousprototypes.com will help me make one.
• Flashrom software on Windows using MSYS2, using build from source guide at flashrom.org.
• I need up2date firmware on the buspirate to program the chip, using:

• https://www.nsideattacklogic.de/en/dumping-spi-flash-memory-of-embedded-devices-2/
• https://winraid.level1techs.com/t/guide-flash-bios-with-ch341a-programmer/32948/56
• http://www.dangerousprototypes.com/docs/Flashing_a_BIOS_chip_with_Bus_Pirate
• https://kean.com.au/oshw/WR703N/teardown/

• Next I need to flash the chips, using a little inspiration from:

The Implementation¶

BIOS ROM images¶

First challenge find the BIOS ROMs which I could flash on the chips. I have tried to extract them from the official BIOS download page Dell Inspiron 3721 System BIOS - A14, 3721A14.exe how-ever I was not able to extract the required files. I found at older version at halabtech.com - Dell Inspiron 17 3721 A12 Bios Files.zip which I will use and later update to the A14 version.

Get both BIOS chips¶

Dis-assemble laptop using Owner Manual and de-solder BIOS chips located at UH2 (EN25QH16) and UH6 (EN25Q32B).

Compiling flashrom for Windows¶

 # Install using https://www.msys2.org and load the UCRT64 environment https://www.msys2.org/docs/environments/
 $ pacman -Syu
 $ pacman -Sy mingw-w64-ucrt-x86_64-gcc mingw-w64-ucrt-x86_64-meson mingw-w64-ucrt-x86_64-ninja mingw-w64-ucrt-x86_64-pkg-config mingw-w64-ucrt-x86_64-python-sphinx mingw-w64-ucrt-x86_64-cmocka mingw-w64-ucrt-x86_64-libusb mingw-w64-ucrt-x86_64-libftdi mingw-w64-ucrt-x86_64-libjaylink
 $ pacman -S base-devel binutils git pactoys cc libusb meson pkg-config
 # <restart MSYS2>
 $ git clone https://github.com/flashrom/flashrom.git
   10  git clone https://github.com/flashrom/flashrom.git
   11  cd flashrom/
   13  meson setup builddir
   14  meson compile -C builddir

Updating BusPirate¶

 $ git clone https://github.com/therealdreg/buzzpirat.git
 $ cd buzzpirat/bin
 # Ensure jumper between PGD and PGC before powering-on BusPirate
 $ ./buzzloader/pirate-loader.exe --dev=COM4 --hex=./oldfirm/BPv3-bootloader-upgrade-v4xtov4.5_Sep-2020_USBEprom.hex --verbose
 # 'Error updating firmware :(' is expected and 'normal' behaviour.
 $ ./buzzloader/pirate-loader.exe --dev=COM4 --hex=./stablefirm/bpv3comp/BPCOMPBZ-firmware-v7.1.12.hex
 # 'Error updating firmware :(' is expected and 'normal' behaviour.

 # FYI: plink.exe is part of Putty CLI, download at https://www.chiark.greenend.org.uk/~sgtatham/putty/latest.html
 $ plink.exe -serial COM4 -sercfg 115200,8,2,1,n
 # Press 'i' + 'Enter' to check for new firmware version

Flashing de-soldered chips¶

 # In MYS2 UCRT64 environment
 $ cd flashrom

 # Connect EN25QH16 chip to SOIC8 test-clip
 $ ./builddir/flashrom.exe --programmer buspirate_spi:dev=COM4 -w 2MB\ \ EC\ \ .BIN --progress

 # Connect  EN25Q32 chip to SOIC8 test-clip
 $ ./builddir/flashrom.exe --programmer buspirate_spi:dev=COM4 -w 4MB\ BIOS.BIN --progress

The Result¶

After re-assembly and soldering both UH2 and UH6 back in place, the laptop booted with 5 error codes, some progress ;-). After replacing the CMOS battery and fixing the terminals (both needed some bending back in place). I give it some more reboots and voila it was working again :-).

Another laptop saved from the junkyard and some interesting stuff learned during the process.