This might have stemmed from a typo in the original instructions (the quotes were messed up after a copy/paste). These steps should help resolve it:

• Log into mysql from the EC2 terminal:

sudo mysql -u root

• Reset your password by re-rerunning the grant command:

grant all on coding.* to coding_username@localhost identified by 'cheese';

• If that doesn't give you an error (it should say OK) then type quit to close
• You should now be able to log in to Adminer with these details:

Follow the instructions on Creating an SSH shortcut then use the command:

sshfs yourshortcutname:/var/www/html/ my_ec2_server