Oh, I just realized what your problem is. You haven't uploaded the config into the device. On every boot you need to upload the full 8KB config file into the device as that's the microcode for the sensor. It won't do anything without it.
Re: Problem reading BMI270 Accelerometer data
I skipped this step in hope it's not necessary becuase I have to figure out how to implement the BMI270_main.tbin.
I will try.