The Original Prusa MK4/MK3.9 is showing the message: "Overcurrent detected on xBuddy heatbed port, disconnect the device."
Error name: Heatbed Port Overcurrent
Error code: #13309 (MK4) #21309 (MK3.9)
The error is shown when there is a damaged cable on the heatbed or any of its connections.
The most likely cause of this issue is damage to the heatbed cable. Check the path between the heatbed and the xBuddy board, and see if there are any parts that are broken or pinched.
In case there is no damage, check the cable connection to the heatbed and to the xBuddy board. Try reconnecting the connectors.
In rare cases, this error message can be shown in case of damage to the xBuddy board. So if the cables and connectors are intact, try checking the board for any damage.