Hi -
I can’t quite understand what you have tried from your question … you wrote “removed the Pi 4 front the Top and that works fine” … “front” - … do you mean “from” … what do you consider to be the “base unit” to be?
My Pi-Top runs with the battery permanently at 0% … It is an issue when the power goes off - which is a pest. … The USB - Power cord is loose, but that is just a matter of not moving it! That works for my application (as a UniFi controller) … but maybe not for everyone