Restoring the original QNAP firmware

If you want to restore the original QNAP firmware for some reason, you can follow the instructions below. Please note that this will only work if your Debian system is still working. If your Debian system is broken but the machine itself works, you can use the recovery mode to restore the QNAP firmware.

First of all, you need a copy of the QNAP firmware. If you made a copy of the flash partitions from your QNAP device, copy the backup files mtd1 and mtd2 to your QNAP device. If you did not keep a copy, you can obtain an image of the firmware from QNAP and extract the files manually:

wget http://download.qnap.com/Storage/tsd/flashimage/F_TS-209_20081024-2.1.2.zip
sudo apt install unzip
unzip F_TS-209_20081024-2.1.2.zip
dd if=F_TS-209_20081024-2.1.2.img of=mtd1 bs=1M count=2
dd if=F_TS-209_20081024-2.1.2.img of=mtd2 bs=1M skip=2 count=4

There are two steps to restore the original QNAP firmware. First, write the QNAP firmware to flash:

sudo modprobe mtdblock
sudo dd if=mtd1 of=/dev/mtdblock1
sudo dd if=mtd2 of=/dev/mtdblock2

Second, you have to restart your QNAP, and then run QNAP Finder to install the QNAP software again. The second step is needed because the QNAP software is stored both in flash and on the hard drive and Debian removed the QNAP software when it formatted the disk.

After you put the QNAP firmware back in flash and installed the complete the QNAP software with QNAP Finder, your device will run the original software from QNAP again.