basically I have netis WF2409E router and i want to update it with custom image so I decided to try fmk. First I added gdbserver to usr/bin and re-packt it with fmk and upload it. After finishing uploading router did not reboot or anything after reaching 100% and it stay as is. So I tried extracting original firmware again and packing it with no changes of files and after 7% I got an error Firmware upgrade fail. So how can I detect what is magic routine for building working firmware.