Wifi worked on OEM firmware (2.1.2 Build 080321 Rel.63639n), but it did not work after installing Lede 17.01.4. ART seems to be erased.
It seems to contain 8MiB flash (m25p64 according to logs). Could it happen that the original firmware fit into 4MB and the ART was placed at the end of the lower half?
I've installed OpenWrt and Lede on numerous hardware before with success. I've also bricked a few and fixed a few in the past using serial and TFTP by reset recovery, but I've never seen anything like this.
Are you sure that it is hardware version v2.0? The wiki seems to indicate the only version with 8 MB flash is v1.0 .
What size was the image that you used to flash?
The location of the ART is not always at the end of the flash, the location is different per hardware model and this is why it's important to use the correct image as the image is built to take that location into account.
It has a sticker on the bottom stating 2.0. The image was 3932160 bytes long. The filename was: lede-17.01.4-ar71xx-generic-tl-wr941nd-v2-squashfs-factory.bin. It would be great if another owner of such a device could verify.