Does file exist using replace to change file extension

I'm trying to determine whether a file exists in a folder and if so exit my batch file.

What I would like to do is pass the batch file a folder and a filename as separate arguments.

The filename will be something like: MyAccessDatabase.accdb

Then, in the batch file, I need to check to see whether there is a file in the folder passed as the 1st argument with a file extension of .laccdb, so I would be looking for the existence of: MyAccessDatabase.laccdb

If that file exists, I would like to display a message on screen for the user: "The application is already open or closed improperly.  If the application is not running, contact Steve"

Then I want it to exit the batch file.  If that file does not already exist, I want it to continue process the rest of the batch file