Power off the device.

Unscrew the 8 screws on the back of the grow box.

Locate the bottom PCBA.

Take photos to document the positions of all the connectors.

Disconnect the connectors shown in the highlighted box in the diagram.

Unscrew the 4 screws shown in the diagram and remove the bottom PCBA.

Connect the new bottom PCBA according to the positions in the photos, and secure it with the 4 screws.

Reassemble the machine.

Power on the device.

Follow the instructions to re-pair the grow box.

Once all steps are completed, the machine should be working normally again.