Your call, but if it was my injector I’d return it. Do you have a spare?

Disclaimer: I did not read all of the previous posts. Regarding the failure to start on the first crank, have you checked the condition of your battery cables, (red?) alternator wire and all your engine grounds? Clean the grounds and replace wiring/cables as needed. I did own a car with a similar problem. Or maybe idiosyncrasy…:) My 90 240 never had the hard starting issue but my 95 850 did that sometimes for years with no repercussions. On that car I finally determined it was a tired positive battery cable that was the problem.

--
Will I buy another Volvo??? We'll see....