New battery first would be the easiest. Possibly someone in your area has one you could borrow. A tool kit that you will need for all the small screws will cost a bit unless you already have one. DJI doesn’t make it easy to take these little...
I've been in the cockpit of a medium-sized propjet at 2500 feet looking for 4 other planes in the vicinity of the same airport we were wanting to land at and with 3 pairs of eyes and knowing where the planes were, it was still very hard to see...
The flight data would show exactly what caused the issue, but the OP doesn't seem interested enough to find out.
It's puzzling why someone would ask for help and then lose interest.
I don't believe you can. Once you create a custom unlock, you cannot fly outside of it, once inside of it. The rest of the world outside the custom unlock becomes an NFZ. That's why custom unlocks should be avoided wherever possible.
However...