your battery could still be knackered, connect the battery charger to the pump instead if it works you need a new battery, if not then you have a problem with the pump.
It could be the pressure switch, to find out disconnect the pressure switch and connect the red wire from the punp to the battery, if it works its the pressure switch that needs changing.
Also if you have a strainer on the pump, this can become blocked with resin beads, take this off and check the pump again.
Finally it could be the pressure switch needs regulating, to check turn the pump on and disconnect the outlet hose from the pump, if the water start to flow again then you need to adjust the screw on the top of the pressure switch, you will need a allen key for this.