Calibrate your first layer with the printer's menu Calibration -> First layer calibration.

The first layer calibration will remove the following message that could appears when you power on the printer: "Distance between tip of the nozzle and the bed surface has not been set yet. Please follow the manual, chapter First steps, section First layer calibration.".

It is possible that with the weight of the Hemera, the X axis is moving down on one side when the printer is off for some time. If this happens, move the X up until it crashes as explained in this step. Note that his can also happen to stock Prusa printer (and so stock Prusa extruder)

After calibrating your first layer, we recommend to set your extrusion multiplier according to our guide here: Extrusion multiplier and filament diameter