Will leaving 4 batteries in parallel and series drain them?
You cannot just wire batteries together at random and expect things not to blow up.

You created two packs.  One has double the voltage of a single battery, one has double the amperage of a single battery.

Then you short-circuit those packs which differ by the voltage of a single battery.  The double-voltage pack will now violently drain into the double-amperage pack.  The double-voltage pack will likely die of over-current while the double-amperage pack will die of over-voltage.

Depending on the kind of batteries, they might melt wires in the process or catch fire.

So now you have your violently reorganising doomsday battery device.  And you put an amperemeter across it.  An ideal amperemeter measures the current running through it without causing an external voltage, so its internal resistance is as close to zero as possible, like a piece of thick wire.

So you now use your amperemeter in order to shortcircuit the remnants of your suicide battery pack and drain all the current it can spare in light of your previous abuse.

Which apparently is still more than the fuse of the amperemeter would have tolerated.

Exploding batteries can cause a lot of damage, but they tend to be comparatively affordable unless we are talking really large ones.  I would seriously recommend that you have someone look over your wiring before and while you start hooking it up with any power source, or your large project might become a pretty expensive project due to destroyed parts.