entity reference view in a view
Your existing view listing all locations is fine for now (assuming a path like "/locations"). Create another display in that view (or a complete different view if you want). This second display/view should first get a relationship to the (location) entity referenced by the field "location". Then the view should have a contextual filter on a node id using that relationship; argument should be in the URL, e.g. by using something like "/locations/%/maintenance" as path.

So if you have two locations (nids: 1 + 2) and 4 maintenance nodes (nids: 3-6), you should see all locations at "/locations" and all maintenance for the first location at "/locations/1/maintenance". Now you just need to link from the first view to the second one by using the correct path "/locations/[nid]/maintenance" and it should be the way you want it. You can take it a step further by displaying all locations along with the maintenance on a single page. You'll need an additional module (if not yet installed): views_field_view.

If that is installed, you can proceed to the next step and include the maintenance view in the location view. Add two new fields, first of type "Content: Nid" and second of type "Global: View". For the latter field choose the maintenance view in the dropdown and enter "!nid" in the argument textbox. By doing this, the current nid of the location is send as an argument to the maintenance view and thus only displaying maintenance nodes that are connected to that current location.