I think this is only needed if you chose to not show the banner when you first loaded it, or if you've hidden it after, and want to show it again without loading again:
"System > On start of layout > MobileAdvert > Show the current banner advert"
I don't deal with PhoneGap. I just use the inbuilt Cordova export to an Unsigned APK. No need to touch config.xml or index.html.
As for the Black screen issue. I can't see why it won't work on the latest Chrome with r71. Either just be sure you are definitely using r71, or try in Firefox ... otherwise I'm not sure.