The hood release handle is apparently ok, but the cables seem to be broken or detached under the hood, but can't open it to find out.
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1998 Jaguar XJ8 Question: Hood release latch under dash does not open hood. How do we get the hood open?
Answer #1patrick mannion from Greg Solow's Engine Room, August 10, 2011, 22:21Master
It's difficult to open the hood if for some reason it's detached under the hood. It's like braking into the car you would need to have another Jaguar XJ8 with the hood open to see how the hood latch works. Try pulling the hood release cable as a friend taps on the hood at the opening end.