Hard brake pedal

Hi there!

My brake pedal has gone stiff on my van. When I'm driving it it will not allow me to stop immediately and gradually allows me to press down.

I have tried pumping it with the engine of but there is hardly any room to pump as it is already stiff. When the engine starts while my foot is pressing the brake it goes down, (although not fully).

I had tried drilling out my own grommet from beside the fuse box (beside where the other cables were coming into the cabin) under the glove box.

I had gotten through two thin layers of steel but stopped when I seen a third.

When I press the pedal while the van is off I can hear an air leaking noise coming from that direction.

Would these symptoms suggest I've hit something I shouldn't have?

Thanks!