Your Helix is probably the 3 pump system compared to HFarr G6 (6 pump) system.

You should have 3 ball valves under the floor to the thru hull fittings that feed water to the pumps.
The pumps have a single output that fills the bag at the bottom. It is also the same line that drains the bag by spinning the pump in reverse.

I would suspect the water line is either cracked or came off the pump. Removing the walls in the back will expose everything. Should be 2 on the port side (1 rear, 1 center) and 1 oump on the starboard side.

Instead of stacking bags I would use lead.