There are several modules used (tank capacity, AC/DC rates, air temp, etc.). I am thinking that one of these modules has failed. Do all the readings show "X" or just specific readings - like for tank levels.
You said you have an "Aladdin Jr", I have the "Aladdin", I'm not sure what the difference is.
But if the Jr uses the separate modules, then I will bet that is where the problem is.
On my coach, those (four) modules are in the rear compartment where the waste tanks are located.