I've ordered my WL-WN579X3 on Aliexpress in mid November 2021, it was delivered in the beginning of December. Marking on the box and device: Aerial X (no model number/WL-WN579X3 anywhere) rev.3
The factory firmware didn't accept openwrt image, reset and/or WPS button didn't trigger the tftp mode on boot-loader… time for serial.
To pen the case you need to remove 2 screws (PH1 in my unit), the case was well fitted, snug and no seams were apparent. The case is held (apart from the screws) with 2 side clips (can be opened with fingers/nails, but plastic prying tool is much better).
Led panel/wps button are on a separate pcb on the top part of the case connected with a ribbon (it's best to remove it when you open the side clips, but it will fall out without damage if you tag while opening)
There are 2 other clips on the bottom, but I haven't found a way to open them with a tool - just open the case.
Serial pads are 4 through-holes in a strait line (perfect for male jump wires, so no soldering or gluing is needed). Vcc/TX/RX/GND - Vcc is denoted with a square pad (in my unit) - use 3.3V ttl adapter, connect TX,RX,GND (TX goes to RX on TTL adapter, and RX to TX). Serial settings 57600-8N1.
Uboot scrolls very fast after power on, I've used option 1 - tftp to ram.
You need a tftp server (openwrt page for rb750gl has good description how to set up one: https://openwrt.org/toh/mikrotik/rb750gl), for this you need the initramfs-kernel.bin file.
After selecting TFTP to RAM, uboot will ask for ip for device, server and image name (default firmware.bin).
After it downloads the image it will boot openwrt, connect to it with ssh, put full image sqashfs in /tmp on the router and flash from cli (it will probably sever the connection when flashing, you can somewhat see whats going on on the serial connection), the router will reboot to flash/openwrt, reconnect the led/wps panel, snap the case, put the screws back and enjoy…