While I cannot say with certainty, it seems that you may have damaged your bootloader by trying to flash the SD card image to the device directly. As I said above, I think the SD card image was to supposed to be written to a card... insert the card, boot the device, and then use the sysupgrade image to write to the internal storage.
I could be wrong about the specifics of the upgrade process, but your boot log does seem to confirm that the bootloader is not working properly anymore. You will probably need to find a copy of the bootloader itself (possibly part of the stock firmware image??) along with documentation about how to recover the device from this state. With any luck, someone on these forums may have experience with your router... but I'd start searching the internet (specifically the manufacturer's website (support site/forums), among other places).
Write the image to a SD card then try to boot the card.
Note that the SD images on the server are compressed with gzip (.gz extension) so they have to be uncompressed before writing to the card. The Linux command below will do both in one step by piping the output of gzip to the input of dd.