Thought I'll post a follow-up to my own question so it may help others in my shoes...

Ok, managed to learn some Nano editing using this site

http://staffwww.fullcoll.edu/sedward...troToNano.html
http://staffwww.fullcoll.edu/sedward...dCommands.html

Made the required changes and restarted sysuid from the unrestrictued system-ui submenu in Settings. Unfortunately, it did not work, but did show "0.8" denoting 80% battery, followed by 80% in the status bar. Which sort of makes sense because I replaced icon with label. However, my N9QT tweaked menu icons that displayed prior to making this change vanished!

Now, what I did not do was reboot N9 concerned whether that may get me in more trouble like previously.

At this point, I reverted back to original conf file (luckily had saved a copy - phew!), and rebooted. My status bar and menu extensions all came back to original display... I'll leave this quest for battery icon and percentage until I hear more advice...