I don't think you should see any change in the meter reading + or - so it appears you have a leak somewhere. You won't really be able to have a good go at it without a fully charged battery to give you the proper voltage readings, anything else would just be luck-of-the-draw troubleshooting.

A positive attitude may not solve all your problems, but it will annoy enough people to make it worth the effort. Herm Albright (1876 - 1944)