Hood release
 

I'm attempting to open the hood of a 1977 Mercedes. The latch in the front end of the hood moves, feels to have spring in it but the hood will not release. Not my car... it was my Dad's and I'm just trying to get it open to check the oil before starting it up and getting it ready to sell. I see no hood release on the inside of the car. HELP. Any suggestions would be grateful.
Thanks!