Please find attached a different RS485 protocol document, sent to me by IC GOGOGO Store for the BMS I bought from them.
I have also just received their RS485 Dongle.
The Dongle plugs into the BMS but the dongle ends in 3 bare wires at the other end. I presume these are RS485- GND, A+, B+.
I have connected these to an RS485-USB dongle.
Any experience with this setup.

I tried your RS485 protocol but did not receive any bytes back.
So looks like this BMS may use a different protocol.

Any chance of adding this protocol:
RS485-english.pdf