There is no auxiliary battery on the ST. You can try resetting the BMS. I did this to mine about a month ago and the ASS has started functioning again after not working for months. i still have the original battery in my 2020 ST.
https://youtube.com/shorts/XR33FBIb3NU?si=pu8XHLcdZ5uxLe_I
https://youtube.com/shorts/XR33FBIb3NU?si=pu8XHLcdZ5uxLe_I