UL indicates child lock on the documented AQUA units. The function is disabled using the procedure for the specific model; there is no single key combination common to the whole brand.
The official AQUA FAQ points to the child lock section of the manual. A button press copied from another screen may activate a different option.
Check the function and the unit's status
Identify the full model number and locate the controls assigned to the child lock. Follow the conditions and duration indicated for that machine. Then check whether UL disappears and whether it responds to the operations allowed at that moment.
Disabling the user lock does not guarantee immediate opening. The lid may still be held by hot water or spinning. If the warning is H after interrupting drying, consult that cooling phase; U4 here refers to detection of an open lid.
If UL has been properly disabled and the lid or controls still do not respond, record the status and request help. Repeatedly restarting does not replace checking the active function.
When requesting support, make clear whether UL is still present or whether it has disappeared and what remains is a lid that is still held closed.