"Borrowing" an aircraft.cfg sounds daunting, but it mostly isn't.
Start with a similar aircraft that you know is good. Rename your "bad" cfg file to something you'll recognize. I use aircraftO.cfg.
Copy everything from above (and including) the [General] section of the "bad" cfg and replace all that data on the "donor" cfg file.
Next, find the [Contact_points] section in the "bad" cfg and copy all of that. Again, replace the contact points on the "donor" cfg.
Next, find the [Views] section on the "bad" cfg including the "eyepoint=" line and replace that data on your "donor" cfg.
At this point, you're ready to test out your new cfg file. If the problem is still there, you'll need to swap-in the .air file from your "donor" aircraft.
Don't rename the "donor".air file just yet. Just change the "sim=" line of one of the [fltsim.X] lines to the new .air file. You also may want to highlight the new .air file then right click and select "properties". You'll see the name of the .air file as Windows sees it. Highlight the name and COPY/PASTE that name to your "sim=" line. Some .air files can use "-" and "_" combinations along with capital and lower case letters that will drive you nuts.
It sounds like you have a classic "dead battery" problem except that
shouldn't shut down the engine.

If your plane is using "hybrid" flight dynamics, almost anything is possible. It might be as simple as adding a generator switch to your 2D panel. Try swapping in a better aircraft.cfg and see how that works. At most, you'll need to make some small edits to the gear height in the (Contact_points] section. Once you have the problem fixed, you can try swapping in engine data and drag/lift data from the old cfg file but work in stages and keep testing.
