: ::::If i couldn't get to the supply area I would crimp the tube a couple of times and sweat the end with solder. They do it on freezer and fridge copper lines so I don't see why it wouldn't work in your situation.

A 1/4" compression stop will provide temporary relief. If cutting a hole in the ceiling will provide access then that is what you should do. It is probably only a matter of time until it starts leaking at the valve pipe connection. LonnythePlumber