If you can find the serial port and communicate back and forth with it, then you may be able to flash the unit as the data is expected to be sent over the serial. However, there's a chance they remap the serial pins after startup, in which case you'll be out of luck.
This board has a "Mobu W6-1014" chip (16-pin) that I have no clue what it's for. It might be wired up to the nearby ATMEL608. The 6-pin header with pins is for connection to the main-power board (3 control signals for 3 relays, 1 ground and 1 VCC maybe 5 v I haven't measured it). There are a couple of pad areas (8 pads plus a resistor) that might be for flashing? If it will help, I can take some time to trace where on the 8285 these pads go if there's interest here to understand this board.
I bought a few of these on ebay, and according to the product details on the ebay page the Make is "MUCH(r)". It uses an eWelink app to control it. I have since ordered a few other switches from another vendor, this time the Make is "Sonoff" - I home these are more understandable from a flashing pov.
Regarding the "Mobu" chip - I've come across the "Mobu official store" on Aliexpress, and these are wifi wall switches. Seems more than a coincidence that there is a "Mobu" brand of wifi wall switches AND a chip with "Mobu" on it.