You might try this. It worked to open my stuck 95 855 hood which was also locked down on the passenger side. If I recall correctly the hood design is the same. Try pushing down hard on the hood near where the hood meets the passenger fender at the passenger wheel well while pulling on the latch release at exactly the same time. You might need to enlist someone to help you. If that doesn’t work try pushing on the very front of hood near the latch. Experiment with different locations to push on.

This is an alignment problem. A clue is to check the gap between the hood and passenger fender. If it is out of alignment (gap is not straight) then you’ve found your problem. If you get it open lube the entire cable and the latches. If you are lucky that will fix the problem.
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Will I buy another Volvo??? We'll see....