I have suffered from this on several Alpines in the past. The hood (bonnet) latches with a dual mechanism. One part is shaped like an arrow head and goes straight down, pushes the locking lever back and this then springs back behind the arrow head to hold it closed. The second mechanism is basically a hook that locks over a lip on a plate that bolts on behind the arrow head assembly on the hood. When you pull the hood release, both should move back and undo simultaneously and the hood should spring up. If they are out of adjustment it can be tricky to release.
On the parts picture the arrow head is 84, the hook is at the front of the locking assembly 88 and the metal lip for the hook is 83
This problem is an absolute pain on Alpines and is unfortunately quite common. On later cars they changed the solid rod for a cable....... that frequently snapped!
First thing I would do is get a friend (or two) and try holding the release fully open and 'bouncing' the hood up and down. Protecting the paint put some soft wood in the gap between body and hood at each side and try to gently encourage the hood to spring free. If it isn't an adjustment issue and it won't come free you will have to loosen the hood by undoing the 8 bolts at the hinges at the front - 81 in the drawing. (On my own Alpine a previous owner had stupidly welded the hood to the hinges which was a bit of a problem)!
Sometimes you can get to the bolts securing the hood without removing the badge grill bar. You need small hands and small tools to do this but it is possible. If you can't and have to remove the badge bar then from inside the front wheel arch you can usually locate the nuts that hold the 'eyebrow' finisher. They will probably be covered with years of mud and muck and will take some finding. If you undo the nuts on the ones at the outer edges you can pull the eyebrow forward a little and then undo the screws at each end of the horizontal badge grill bar that sit behind it. Once the outer ends of the centre bar drop down you will be able to get to the 8 bolts, undo them and lift up the front of the bonnet a little and with the help of a second person you can usually jiggle the mechanism free by moving the hood around with the release held out.
This is not a fun job. On my own car I keep a safety wire around the locking arm on the release mechanism (see photo) and leave it hanging down into the engine bay. If I get this problem again I just need to reach up from underneath and pull the wire and it releases the hook lock which is normally where the problem is.
I hope that this helps you.
Tim R
The picture above shows two of the eyebrow fixings from inside the front wheel arch.
The picture above show the bonnet lock mechanism and my 'safety wire'.