A7A5 warning in ABB DCS880 drive indicates mechanical brake opening not allowed. This means open conditions of the mechanical brake are not fulfilled. 

The brake has been prevented from opening (lifting) by 44.11 M1 keep brake closed, 44.12 Brake close request or torque actual does not reach 44.10 M1 brake open torque, during torque proving.

1. Check the mechanical brake settings in group 44 Mechanical brake control. Especially 44.11 M1 keep brake closed and 44.12 Brake close request.
2. Check that the acknowledgement signal, if used, matches actual status of brake.
3. Check the used digital inputs and outputs (groups 10 and 11).