If you order in aliexpress a thermal camera MLX90640 and you can't make it work with a raspberry pi, check that is not a GY-MLX90640.
For that you can use the serial port instead of the I2C port.
All the code and info is here:

https://github.com/vvkuryshev/GY-MCU90640-RPI-Python

GitHub - vvkuryshev/GY-MCU90640-RPI-Python: The script to connect the thermal image module GY-MCU90640 to Raspberry Pi.

The script to connect the thermal image module GY-MCU90640 to Raspberry Pi. - vvkuryshev/GY-MCU90640-RPI-Python

GitHub