Thanks for the video, better than nothing. The light pattern and physical build is identical to PinIdea RR-210, this just backs up my guess that DaYun is indeed PinIdea under a new name.

I would try to log into the controller and stop the miner process, then attach to the serial interface of the failed board using `screen` or `cu`. You could additionally try to connect to the serial interface while the miner process is running, and see if it replies at all. The problem with debugging on PinIdea rigs is that they do not interface with the hashboards directly a la Antminers, but instead the controller communicates with a small CycloneV FPGA. So, due to a lack of debugging information from interfacing with this FPGA, the most I can suggest is comparing rails between working and non-working hashboards, and seeing if the chips are even coming online.

For the image file, 7-zip FM is a good choice to analyze the image. Another useful tool is photorec/testdisk as well as binwalk, these can help you unpack old deleted files if they did not properly create the image.