How to replace the circuit board in the charging station on the Husqvarna Automower 320, 330X, 420, 430X, 440 and 450X
The circuit board in the charging station controls the signal sent to the robotic lawnmower. It is easily affected by lightning strikes due to the boundary wire acting as an antenna. If lightning strikes nearby, a power surge can travel through the boundary wire into the charging station and the first thing it hits is the circuit board. If a power surge occurs, the circuit board may be damaged and may stop working partially or even completely.

The error message that the robotic lawnmower most often displays if the circuit board is faulty is "no boundary signal". Then check the colour of the lamp in the charging station. A green glow is an indication that the boundary is OK and the circuit board is working.
However, if the lightning has affected the circuit board, this may be a false signal. Start by unplugging one of the boundary wire cables to see if the light starts blinking blue, which it should if the circuit board is intact.

If the light still glows solid green, even though you have unplugged a boundary cable, this is a signal that the circuit board is faulty.
If the light also flashes blue even though the boundary cables are connected correctly, it may be because 1. the circuit board is defective,2. the cable is defective. You should measure the resistance of the loop to check if it is intact or faulty. A value below 20 Ohms is a sign that the loop is OK (the value should be as low as possible, but usually it will work below 20 Ohms). If the value exceeds 20 Ohms, the loop should be checked and repaired.

We will now go through, step by step, how to disassemble and replace the circuit board in the charging station of your Husqvarna Automower.

Tools we use: Torx screwdriver T20.
Remember to use anti-static (ESD) wristbands when working with circuit boards to avoid the risk of damage.

Step 1: Loosen the two screws holding the front of the charging station tower as marked in the picture.	Step 2: Press the button on the charging station cover to release forward. Then lift the cover upwards to remove it from the charging station.
Step 3: Now we can see the circuit board which has three contacts connected. Remove the contacts from the circuit board.	Step 4: Remove the circuit board. The circuit board is held in by two plastic tabs. Carefully bend these outwards to remove the circuit board from the charging station.
Step 5: When the old board is gone, it should look like this. Take care to check that the cables and connectors are intact and in good condition and that the connectors are free from corrosion.	Step 6: Carefully install the new circuit board by bending out the tabs and sliding it into place.
Step 7: Reconnect the connectors and make sure the circuit board is firmly placed in the charging station.	Step 8: Replace the cover in reverse order and tighten the two screws.
Step 9: Now reconnect the charging station to the lawn. Check that the light is glowing solid green. Finally, we need to pair the robotic lawnmower and the charging station circuit board. This is done by pressing menu->security->advanced->new loop signal. The robotic lawnmower will then confirm that a new loop signal has been completed.