Draytek Vigor2830n

I try to add support Draytek Vigor2830n.
The first problem is loading the firmware into the router.
There is no way to use the UART loader since I can not find Boot_sel0.
There is a firmware dump from the flash.
But there is no ability to find in the bootloader the algorithm for calculating the checksum.
The structure of the update file and the rest of the information I found is reflected in the WIKI page.
I will be grateful for any help.


I think a person familiar with the MIPS assembler will help