The max has no pressure sensor.
In typical Sovol fashion the firmware is only available at the (semi-secret) OTA link. You should be able to force a OTA reinstall from the Sovol UI on the touchscreen.
The Z offset is determined using the eddy sensor. As the eddy moves closer to the bed the output frequency changes at a steady rate. When the nozzle touches the bed there is a momentary fluctuation in the eddy output.
Power down your printer and make sure both ends of the cable to the eddy are firmly inserted. Several users have reported loose connections, likely due to vibrations during shipping.