Try to do a search on this forum, this (url below) is the only place I know with all the firmware collected.
https://files.scooterhacking.org/
But does not have your said version.

If bluetooth connection is the issue why not try st-link or CP2102 UART to USB using IAP app. So far ST-Link it working flawlessly for me for SNSC 2.3 controller and BMS. My issue is flashing the dashboard. No matter what I do it does not work flashing those rental dash.

This dashboard looks exactly like the one I posted below, https://www.scooterhacking.org/forum/viewtopic.php?f=26&t=925 Try and see if you can find the C2 Capacitor to remove at the back of the board beside the black cable. So far I have tried to flash and failed using STLINK. Even UART to USB is no...

Does anyone know how to flash these new dashboards (scooter with front and back drum brakes)? Is removing the C2 capacitor necessary to flash them? I found a C2 capacitor on the back of the board instead of the front. https://i.ibb.co/sPnL57h/IMG-20221122-213110.jpg (here is a comparison Left is Old...

I think I have read many solutions throughout this forum that this issue with the 10sec shutdown thing is related to the BMS so its either you do a bypass (solder the -ve wire direct to the battery) or you flash the BMS with STLink or IOT.

Have you tried via STLINK?