Hi Steve, tr indicates a tamper return fault. This is the part of the system which gives you tamper protection on the outside bell/sounder.
If it was working before the battery change then most likely you’ve simply pulled out a cable from the terminal. tr terminal is about 12 up from the bottom of the circuit board on the left hand side.
Should be marked tr or tamper return.
I would check this first.
We may have found other answers which could help you.