Take the plastic cover off so you can get to the cables at the latch and try pulling on the cable with pliers. If that doesn't work, from under the car, you should be able to look up and see the bonnet catch. Get someone else to pull on the handle so you can see if the cable is doing anything. If it is and the latch is just jamming, get a length of steel bar, thread it up and tap on the end of the catch. That should pop it open. If the cable has broken then you need to release the catch which is a whole different ballgame.
Take the plastic cover off? IMHO you only can remove the grill when bonnet is open...
As for the steel bar you are right, I used a piece of pipe of about 1 meter length, filed openings in it as by the drawing of about 0.5 cm wide and 1cm deep.
Put suspension on high (leave a frontdoor open) and carfully work your way up from behind the foglamp, along the steering box and over the latch lever and turn the pipe to open the latch.
It is a bit fiddly and you probably extend your vocabulary but it may work.
Edit: can't get the 'manage attachments' to work, here's the link to the drawing: