I have the same problem with opening the bonnet on my Ford Focus CC 2007 plate – it just went - I’m not a mechanic or into the workings of a car so as my Dad (76) used to be in the garage trade I asked him to see if he could help by following this thread – working through the grill we managed to remove the rubber boot using a pair of long nose pliers, we then used a very long screwdriver through the grill and pressed in the white collet as indicated whilst turning the key, we tried this several times to no avail the bonnet just wouldn’t pop.
Instead of removing the grill and risking damaging it (£82 quoted for a new one) Dad then put the car up on axle stands and removed the guard underneath the engine and went in from below.
He managed to locate the bolts holding the lock mechanism and after much cursing and swearing (goes with the job apparently) he managed to loosen the lock mechanism so we managed to force the bonnet open – be careful here not to tug too hard as the alarm is connected – unfortunately we broke the retaining lug for the alarm whilst doing
We then removed the actual lock and cable etc only to find that the white male plastic cross mentioned above had one of the tabs missing, the connection between the lock connector and the lock mechanism had obviously been loose for some time as the inside of the lock mechanism was also slightly worn, (a bit like when you have a cross head screw and the metal is soft and eventually the cross wears away).
With the lock barrel etc out we tried the key in place and this turned the white plastic cross section quite easily, however when we applied a bit of pressure to the white cross by holding it still with a pair of pliers the key failed to turn it, so it implies that there is a problem with the actual lock itself.
So after all that it looks like I am going to need a new lock and the lock mechanism, The cost appears to be about £100, but I’ll probably have to get a locksmith to set new lock as well.
As an interim measure we have left the lock out and I have a long piece of steel which my Dad has made so I can go in through the grill to turn the lock mechanism to release the catch.
As you can imagine he had plenty to say about the design of this particular piece of kit!!