This is not an uncommon problem with the XiaoXiang play store App. There are a couple things to try.
Enable Location in your system settings
Reboot the device
If it asks for a pin, use 123456
If you still can not log in to your BMS, please submit a trouble ticket and we can provide you with an “admin” version of the app that has a much higher success rate. It comes with a LOT of options that can alter settings within the BMS.
Below is an App walkthrough we did comparing the “consumer” version to the “admin” version.