Unable to validate salesforce credentials in power bi service
Solution 1:
Go to Salesforce, find the connecting user and at the bottom there should be login history. Do you see any errors there? Maybe "Restricted IP" (ask your SF admin to check this user's profile & allowed login IP ranges), maybe "Security token required" (ask sf admin, there's something you need to append at the end of password)...
If your app uses "connected app" (set of OAuth2 keys) there might be some config in SF needed like "all users can self authorise" or add your server to list of allowed callback urls...