When you have a DTR battery without voltage, you must measure with a multimeter these battery pins https://ibb.co/XzpWLSd
If your multimeter marks this resistance measure https://ibb.co/Vpj7Cg1
It is very possible that the battery has broken this terminal https://ibb.co/VWmw6zG
To repair the problem You will have to make a welding point and problem fixed