Drain errors stored and the pump not running looking for power to it I found open. Door is locked and will not open

My experience has been that the MCU controls the lock, drain and motor functions. I would be inclined to replace it before the UI. I also had another unit that I replaced CCU because the diagnostics pointed to the CCU board having a bad pump driver. Replaced the board and customer was able to complete one load and then unit stopped draining again. What I found was the drain pump was drawing to much amperage and causing the CCU failure. The pump I had ohm ed out fine too, do not remember if I found a amp or wattage reading possibly on the side of pump? Replaced drain pump and problem went away. I installed original board at customers request, but turns out the original board was too badly damaged to run drain pump. The door on your machine will remain locked until machine senses the water is fully drained.
Examine the drain pump motor housing, I am willing to bet you will find what I did, motor housing full of water. Let me know if this helps.