optima 2 plus tamper light and "c" light up ?

My Optima 2 Plus alarm went off the other day ,wew put the code in and reset then it did the same during the night we diconnected the battery and removeed the fuse on the mains power . I put a new battery in and connected back up cover on but the tamper light came on and "6" .I now have a tamper light on and a "c" showing can any one help please