Fault with nexus 8 burglar alarm?

After a power failure my nexus 8 alarm remote pads would not reset basicaly my code would not work , got the maual and tried the factory code to reset 1234 still would not reset , finally as per manual removed connections from battery inside box and aux fuse , refitted and went through engineers prog 7890 , all okay. Codes on remote pads come up rr t5/t6/t7/t8 but still can't reset , any body out their got any hints