If the front end damage didn't totally disable the release cable you might try this: while someone pulls the release from inside the car (and hold's it out) try pushing the hood / bonnet down and then pulling up. If it doesn't open you might also try (while hood release is held open, again) "bouncing the front of the hood. Try other variations on this such as (if you can) pulling on the lip of the hood forward (toward's you). Two people working the hood while the release is held open might help. If the grille is so damaged as to need replacement perhaps you could cut a hole in it and see if you manually work the cable release or the latch itself.