Also U02 is user code number two.
Do you have any other codes to try?.
User code one for example,also what lights are lit on the keypads other than the tamper?.
Use the add question box below to add additional info,start with the model of the panel,lights etc.
Sounds like you have created a tamper by removing the lid and it needs user1 or engineers code to reset :).
e manno
September 2013