Check the Hood Cover Motor
I to had this problem a few years ago; if your hood cover doesn't open it's usually a problem with the electric motor that holds the cover in the shut position by default, when you press the switch it activates the motor which opens the hood catches using quite a crude method of pulling cables to onlock the catches, the cover then opens with the aid of gas shocks and the Hydraulics to close it.
Sensers then allow the hood to operate once the cover is out of the way.
You can actually open the hood by slacking off the cable, the tension on the cable in the closed position stops the catches from opening, so once you start to slacken off the cable the cover will open, the motor does exactly the same thing.
It seems over time and lack of use the cover motor tends to stick and as mentioned earlier a tap from a small hammer will sometimes help it out, however and in my case take the motor off and take it apart to clean the brushes and armatutre making sure all the cables & linkages are ok clean and grease if required.
Be carefull when taking this unit apart it's not the best made motor so watch where everything goes!!