I have had this problem with a similar car. The solution was to loosen the 10mm bolts that hold the release mechanism on the side that was sticking, and push the mechanism downward a bit and then re tighten. It seemed a bit counter-intuitive, but the release mechanism works better if there is a bit of tension at the latch. Lubricating is always a good idea too.

Good luck!

Grease up the latches. WD40 works for a short while, I use spray lithium grease. Spray into the plastic boxes where the mechanism is.

While the hood is up and after you greased the latches, go ahead and work the release cable many times to spread the grease around.

Don't forget to spray the hood hinge points once in a while either.
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Keeping it running is better than buying new

I am no expert on fixing your problem but -

On 850s you could remove the grill without opening the hood. There were instructions on Volvospeed.

The next time you open the hood, see if you can do that on your car.

On the 850, it was easier if you turned the clips in one direction.

This would be real handy if your hood goes bad.