wild guess, the starter got flooded, i'd bench test it.

Try getting a wrench on the end of the crank and rock the crank a little. The starter might be jammed in the flywheel teeth. Maybe.
volvolugnut

I didn't think they had them on the P2 but been a while since I pulled a couple of spares for our son's car for the 'just in case pile!' The bracket most didn't re-use and I think the later P80 cars and P2 have smaller physically starters, so the bracket is overkill. Good luck! You could try jumper ...

If you go to junk yard, then starter motor design changed after 2006, so 2007+ starter has different number of teeth and connector.

Not sure why Volvo did this change bc it is the same engine anyway...

If it is the starter, maybe it was on borrowed time and just happened to quit.