some report from myself.
after a few days of research over google. I found 0 articles discuss about ts5400d .(exclude all the ads and open box review)
try to get the 5400d into em mode. But no clue, try all the other method and the pc still unable to detect the NAS.
If this model unable to connect with tftp. The only step i can do is request the initialize usb recovery image from your guys.