08 Rx8 with new battery won't crank or start.sat one year

It won't crank as in turnover? Or it's turning over and will not start?

If you turn the key and nothing happens at all, then the first place I would look is the starter and related fuses. If its turning over and not starting, the engine is either flooded from sitting for a long period of time, or the seals have worn away from sitting in fuel so the engine cannot create enough compression to start.