I may have a same problem you mentioned above, i.e. the ‘rescue’ image can’t rescue
I did according to the instructions here, but when I powered the board, no any led was lighted.
I also tried the way @jbastosn said in which he has booted up his board, i.e. using "qualcomm dragonboard410c_sdcard_install_android-99.img" to install Dragon, but it didn't work either, there was only one blue led (BT/WIFI) blinked once when I powered on the board with the sd card inserted into slot.
I got this dragon at SFO15, it worked then, but I haven't used it for a long time.
Is my Dragon board bad? If not, could you give me some suggestion, what should I do to retrieve my board?