1)Push the lever forward.
2)Get someone to push up and down on the front of the bonnet near the centre were the catch is.
3)As they are pushing up and down so moving the bonnet slightly pull the lever backwards. You may have to wiggle it bakc and forward to get it to move. It should eventually pop the bonnet.
I regular have to do these types of thing to the 45 cars my mate has stored on his industrial units site. To get the bonnets open.