check there is hydraulic fluid in the pump (it has a gauge on the side. Also checked that the tbar peice that sticks out of the pump is fully closed.

What also can happen is the hydraulic rams can come un bolted from the hood frame - this can damage the hood and frame badly so i would check that as well

Worse case senario would be the pump is knacked and thats mega bucks for a new one.

hope this helps