I ran into the same problem hanging while attempting to chainload, so found your posts and decided to bite the bullet on 1st stage, and it works, as in the device is not bricked, but booting into openwrt 15.05 was a no go. I need to figure out where to copy the zImage and dtb file. This could be the vague instructions at the end of the openwrt wiki NOTE: Remember to note down the mac address bby elchanguito - uBoot