Start Fedora. When it tries to run X, the screen goes black you say, press Alt+Ctrl+backspace
This would kill the X. Now login and give the command
This would open the file. To edit the file, press the key 'a'
--INSERT-- would appear at the bottom left. Now you can edit the file. To save and quit press
That is -- hit escape followed by colon(
and then write wq.
To exit without saving