Hi 1000001101000,
Firstly, I apologize because I could not keep my promise to deliver the instruction soon enough. Covid 19 hits hard on my location and the last 8 weeks were a nightmare for me, extremely exhausted. I just start my holiday leave today. So here my instruction, my English is not so good, if you feel something confusing, please tell me, I will try to do it better.
1. SOFTWARE:
CH431 programmer:
https://www.win-raid.com/t796f16-Guide-Using-CH-A-based-programmer-to-flash-SPI-EEPROM.html HxD hex editor:
https://mh-nexus.de/en/hxd/2. PREPARING THE CH431 CHIP PROGRAMMER
You need to check the datasheet of the bootloader chip to confirm the chip operating voltage (5v or 3.3v). applying the wrong voltage can damage the chip and corrupt the bootloader data.
If you have the generic CH431 chip programmer similar to this
https://www.amazon.com/dp/B07R5LPTYM please make sure the chip programmer can operate at the correct voltage level when you change the jumper position, some chip programmers have faulty design and only work in 5v mode.
You also need to check the datasheet of the bootloader chip to confirm the chip operating voltage (5v or 3.3v). applying the wrong voltage can damage the chip and corrupt the bootloader data.
How to check if you got a faulty programmer and how to fix it to work in 3.3v mode (little soldering skill required)
https://www.youtube.com/watch?v=-ln3VIZKKaE How to use the chip pro programmer
https://www.techinferno.com/index.php?/forums/topic/12230-some-guide-how-to-use-spi-programmer-ch341a/ NOTE: red wire of the CH431 programmer clip must be connected to pin 1 of the IC
How to determine PIN 1 of the chip (source: internet)
3. BACKING UP THE ORIGINAL BOOTLOADER FROM THE ROM CHIP
You if you can read the data from the bootloader chip, please save a backup of this file. I call it the old bootloader file.
4. EXTRACTING THE UP THE NEW BOOTLOADER FROM FIRMWARE UPDATE PACKAGE
Download the firmware update package for your NAS, change the extension the u-boot.img to u-boot.zip.
After extracting the zip file you will have a folder contain multiple *.bin files for different nas models. In my case, I pick the u-boot_lswxl.bin file for my model.
5. PREPARING THE NEWLY EXTRACTED BOOTLOADER FOR FLASHING
Using a hex editor, you can compare both backed up and newly extracted *.bin files. You can see that the backed up bootloader*.bin file is slightly larger than the newly extract *.bin file because the backed up *.bin file contains additional important information, such as MAC address ( xx:xx:xx:xx:xx:xx format), serial number, and other configuration of your NAS.
You need to copy all these additional information from the backed up *.bin to the newly extracted *.bin file or your NAS cannot work. Make sure these additional information are pasted into the exact begining address ( or offset) and save your modified *.bin file.
Left - newly extracted *.bin file, Right - backed up *.bin file
If you flashed the chip successfully, the NAS power LED and function LED can change state and color when the NAS is booting up. NAS Navigator may detect the NAS in Emergency Mode, and you may need to modify the LSupdater.ini to force the NAS to update the firmware. Please follow Buffalo official instruction for further steps.
