If the panel does not light up, check if the machine can be reset when powered on.

• If it can be, then check whether the connecting plug between the panel and the mainboard is secure. If there is no loose connection in the wiring, replace the panel.

• If the machine cannot be reset when energized, check if the mainboard indicator lights up (the 6442 mainboard has LED indicators on the outside of the board, and the indicators for the KN332 are on the inside of the mainboard and need to be carefully observed).

1. If the mainboard does not light up, use the steps in "Mainboard indicator not lighting up" to troubleshoot.

2. If the mainboard does light up bright, check whether the connection between the panel and the mainboard is secure. If the connection seems secure, unplug the connection and reconnect. Check whether the machine can be reset upon being powered on.

• If it still cannot, replace the mainboard with a new, identical one.

• If it can, you will need to check the input voltage of the mainboard. As shown in the videos, measure the voltage of the plug with the mainboard power supply plug plugged in and unplugged.

• If the mainboard voltage is always 24 V, irrespective of whether the mainboard power plug is plugged or unplugged, replace the mainboard with a new, identical one.

• If the voltage remains 24 V when the plug has been removed and does not when the plug is inserted, then remove all the plugs on the mainboard but the power supply plug and measure the voltage of the power supply plug again.

If the voltage of the power supply plug of the mainboard returns to normal after removing all the plugs on the mainboard, it means that one or more of the accessories connected to the mainboard are short-circuited. Plug back the plugs on the mainboard in turn and repeat step c to sort out the faulty plug(s) (Accessories that may be problematic are: the X/Y-axis limit, the autofocus sensor, and the open-cover protection sensor)

If the voltage remains not right after all the plugs of the mainboard have been sorted out, replace the mainboard with a new, identical one.