Mindful that this could happen suddenly at any time, although i guess it might be rare, i had a bit of a fiddle today. I've threaded some small diameter, very strong wire through the same hole that the release cable enters the catch, and wound the wire around the catch (the part that moves when you pull the lever) and out through the same hole, and left a loop in it. i then joined some more wire to it, and routed the wire along the fire wall and dropped it over one the brackets on the firewall, my car is RHD so LHD drive cars may be different, but i'm sure there's a bracket you can use. I put some PVC cable insulation on the bracket so the corner wasn't sharp and dropped the wire down, it hangs down just next to the oil filter. i joined a jubilee clip to the end, a nut would suffice, to act as handle, or you can put a bar through it to give more leverage if needed. With some force when you pull on the wire the catch will release, bearing in mind my release cable is still fitted, so you're pulling against the resistance of that. If the release cable was broken or became disconnected, there would be less pressure on the catch and it should release relatively easily
I don't have a lift, but i should imagine with the car in the air, you may even be able to reach up and grab the actual looped wire and pull the catch open, without extending the wire down to ground level, with all the faffing about i did lying on my back
Hopefully i'll never need to use it, but a at least i now have the reassurance that i can open the bonnet/hood should the release cable fail
Should have added, if you do decide to extend the wire down over the bracket, you'll need stranded, flexible wire, rather than solid copper, as that would be too stiff. Very strong fishing line or braid would work just as well
