Did you really flash the ADXL or your main board?
According to the error message, your fly_adxl is still on v0.11
If the way as described in the above link is not working, you can try the solution described here: Raspberry Pi Pico + ADXL345: Portable resonance measurement
Yes, fly_adxl is an arbitrary name. You can replace each occurrence with something else.
This sets a specific pin on the RPi Pico MCU that turns off its power saving mode. This leads to a cleaner voltage supply and better readings of the ADXL values.