I start a thread looking for support Reyee RG-E3 router. It is a WiFi 6 router based on MediaTek MT7621 chipset. The FCC page is here: https://fcc.report/FCC-ID/2AX5J-E3.
serial console is probably the four holes in the photo, access them from
the other side of the PCB, if you don't want to remove the heat sink.
once connected, post the boot log.
check if boot loader's interruptable, and post the output of the help and printenv commands.