red light still on continous 9930 system?

MY ALARM SYSTEM 9930 is showing a continous red light under the tool icon, on further investigation its now showing battery missing, I took out the battery and of course the alarm sounded I entered my code success, had the battery checked only to discover it was fully charged ? cleaned the terminals put it back in, but on the panel its showing reset, and tamper lid. ive tried various codes but no joy help ??