Hello,

Its possible that the engine was partially seized.

With your new starter and charged up battery, it should started up nicely after those repairs.

When the car sits for a long time some internal engine parts are without due lubrication (I wanted to say some internal rust may have been formed but Volvo red block don't usually do that in 4 months).

Test the engine to see if its easy to turn. Take a short (1 foot) rachet wrench equipped with 25mm socket (for crank bolt) and try to turn the engine clockwise manually. See if you needed much effort to do that. I don't have any unit of measurement of torque/strength to offer but it should be smooth and easy.

You might be due for oil change too..

Amarin.