Error 2147024891 when performing SQL2012 SP1 CU6 upgrade from SQL2012 SP1 CU3

I am trying to upgrade a secondary replica running SQL2012 SP1 CU3 to SQL2012 SP1 CU6 and it is failing on DQ, FullText and SQLEngine with Exit Code -2147024891. The error is Component Error Code 5 with Access to the path 'C:\Program Files\Microsoft SQL Server\MSSQL11.MSSQLSERVER\MSSQL\Binn\sqlscriptdowngrade.dll' is denied.

I have attempted this 3 times. The first time I was able to upgrade Integration Services, Reporting Services Native, SQLBrowser, SQL Writer, SQL Client Connectivity, SQL Client Connectivity SDK, Data Quality Client and Setup Support Files. I tried 2 more times with the same errors. If I run SQL Discovery is shows all components at build 3381.

Any ideas?

Thanks

Chris