There is a bluetooth module HM-10, taken on Ali. The CC2541 chip, but the firmware version is some kind of left, does not respond to AT commands at all (did the port through the Arduino com, by the way, the other module is connected by commands, but the AT + SBLUP and AT + VERSION commands do not work there either). The question is how to flash it through USB-TTL? I did not find a clear scheme, except for references to a hard reset. 
If you believe this scheme - then you need to close the contacts RSTB and GND. Has anyone done this?
