BMP388 Sensor showing negative altitude while connected to an arduino nano.
Could you please take a picture of how you connected the module with the development board? It can significantly support us in doing trouble shouting.
If the connection is correct, could you please first download the library of the product and follow the sample code on the Wiki page? The link is shown below.
Hope it can help!
Did you use the library and the sample code from the offical wiki page?YeezB