Here is the information to use this tool.
1. On the AuthAnvil server make a folder called c:\authanvil\tools\.
2. Unzip the contents of the zip into the tools folder.
3. From an elevated command prompt execute the tool without any parameters.
4. It will ask 4 questions:.
a. UserName: email@example.com.
b. SiteId: <ID or leave blank for site 1>.
c. New ActiveSync key: <password>.
d. Verify ActiveSync key: <password>.
5. It should succeed.
Tool is located in \\Zeus\Files\CustomerService\Troubleshooting Tools\ActiveSync\ActiveSyncUpdate.zip