Hey there,
TLDR - writing directly the image in the flash didn’t do the trick for me personally but if you get some guidance or find out how to do it, please post it here and tag me as it would nice to learn something new 
You can recover it but I suggest to contact the support team via email to confirm the image you need to write in the flash. I suggest you write in the NOR flash first as that one imho is easier to work with while the NAND is a bit more difficult when you want to just write from empty.
All the mac address, serial number and rf tuning are stored in the art partition which you can get again from support over email and then identify where it is stored and replace it in the flash.
In my case I had another ar300m so I was able to grab the image from there and then replace the art partition. You can read my journey here : GL-AR300M Unable to flash NAND - #33 by misujr and see how I have managed to get it back basically.
BR,
Misujr