Maybe not right place to start, bought an mmvdvm modem for raspberry pi uses geehy apm32

[sysadminpower2019]

Hello,
sorry to ask but can't seem to get much help anywhere else.
i purchased a ham radio modem for the raspberry pi that using an stm32 to run the whole set up.
unfortunately, the pi star software which usually run this device was unable to update the firmware for the board.
it managed to erase it but when it tried to flash the firmware geehy apm32 would not allow it to start in flasher mode.
I don't see any obvious pins or diagrams to set this device in flash mode.

here is a link to the aliexpress seller
https://www.aliexpress.com/item/1005005636431546.html

please set if not appropriate. thank you