Not sure if this was ever resolved but I just received my LAN Turtle and a nearly identical issue happened. I plugged it in, all seemed well but the turtle stopped responding, wouldn't boot, couldn't "unbrick" following the instructions. Nothing worked but the green light. I was writing an email to support when I decided to plug an active ethernet cable into the turtle first BEFORE plugging the turtle into a computer or power source. Lo and behold, the thing booted. If I plugged it in without a cable, it appeared dead again. So I plugged it into my network, then plugged it into my notebook (running Kali) and it appeared to boot. I was able to access the menu and update to the latest config. Now it seems to work fine, booting without the cable. Not sure if there is some ethernet adapter boot sequence in the thing that got swapped somehow or what, but plugging into the network first and then into a computer fixed it for me.