Hello. I just got a Dell Inspiron 15 3558. There is a lock icon with the Escape key, but I can't figure out what it does. Any ideas? Thanks.
The key you are referring to is a fn lock key.
Press the fn key + esc key - it will enable the fn lock - when enabled, you could use the secondary functions from f1-12 without use of the fn key itself. In other words, the secondary functions will become primary functions.
Download the specifications manual here - http://dell.to/2gryrMy- see page 18.
Also, please click my DELL-username and write me a private conversation with the service tag and your Name for case records.
Let us know if you have any other queries.