Enable boot mode on an STM32 aliexpress clone

[sysadminpower2019]

Hello,

I have been trying to update my firmware for this board but have no had any luck. Apparently it needs to be put into bootloader mode but there does not seem to be any obvious place on the board to work with.

Here is a link to the board. Hopefully at least someone can point me in the right direction to try things out.

https://www.aliexpress.com/item/1005006281394445.html

the chip seems to be a geehy apm32 f103cbt6

thanks very much