The panel has its own charging circuit,either the battery is defective, or the panel isn't charging the battery.
Its likely, that when the cable was cut, it blew the AUX fuse on the pcb,or the battery fuse blew when the battery was exhausted,due to too much current pull from the battery.
Either way,
Power the panel down (remove mains power) and check all three fuses located right of the battery terminals,
check the fuses with a multimeter(not visually),
you won't be able to test the battery without a specialized tester, so I suggest you replace it,especially if its 5 years of age.
You have patched up the cable haven't you ?,
you really should of taken photos of the damage, and got the workmans co to pay for the repair.
e manno
May 2012