How to fix a non-loading logon screen (HTTP error 503)

If the following error messages are displayed in the log file, the likely cause is an orphaned mongod.lock file which is preventing the product from starting up properly.

> <date> INFO:Component Resolve Thread (Bundle 3):MongoServiceController> Data service not ready: Timed out after 10000 ms while waiting to connect. Client view of cluster state is {type=Unknown, servers=[{address=localhost:27017, type=Unknown, state=Connecting, exception={com.mongodb.MongoException$Network: Exception opening the socket}, caused by {java.net.ConnectException: Connection refused}}]

> com.mongodb.MongoTimeoutException: Timed out after 10000 ms while waiting to connect. Client view of cluster state is {type=Unknown, servers=[{address=localhost:27017, type=Unknown, state=Connecting, exception={com.mongodb.MongoException$Network: Exception opening the socket}, caused by {java.net.ConnectException: Connection refused}}]

To fix the non-loading logon screen

1. Ensure that no product related processes or mongod processes are running on the system. Then stop all processes and remove the mongod.lock file from the <install dir>/data/db folder.
2. Start Windows Task Manager.
3. In the Service tab, make sure that the Service with the name "bmmadmin" or the description "BMC TrueSight Middleware Administrator" is stopped.
4. In the Details tab, look for processes called "bmm-admin.exe", "bmm-admin-java.exe" or "mongod.exe", and terminate them if any of them are running. 
5. Navigate to the <install dir>\data\db directory and delete the mongod.lock file.
6. Restart the service.