Cheap cavalier

Saw this cavalier for cheap. The door will close but will not stay closed. Any idea as to what is causing this issue?

Also when you turn the key, nothing happens. This is just a dead battery correct because it can be jump started and will stay running.

Bad door latch? With door open, use a screwdriver in place of the "catch" on the "B" pillar......close the door latch with the screwdriver and pull on the screwdriver......if the latch releases, that's the problem.....if it holds, than the catch has to be adjusted....

Yes, it does sound like a bad battery....just double check the battery cables for corrosion.....