GE Front load washer service mode
It should work with below steps:


Press "Power" button to stop current mode if necessary.
Unplug power line for 30 seconds.
Open the door, then plug power line but do not press "Power" button.
With in 30 seconds, after plugin power line.


Close door.
Press "Signal" then "Delay start" then "Signal" then "Delay start".

Door will be locked and show "t01" on display.