No singal to injectors
 

Can't start the engine on my S80 after putting the injectors back in, as well as the cover to get access to the swirl flaps. At first I thought I might need to bleed the engine of air in the fuel systems, prime it but checking some more there seems to be nothing coming the injectors. Nothing coming from the noid lights confirm this.

Anyone know what the most likely issue is and where to look? Looking around most people say either ECU or wiring. Is there a best way to test myself if these are the ones not working?

Fixes even if one of these are faulty? Could battery be too low so the signal is prevented from being passed? What's an ECU replacement like? Is there some sort of reprogramming needed and if yes, why?

I'm guessing theirs no signal because there's no fuel pressure likely due to having bol locksed the injectors messing with them on the bench chasing your tail with a problem you were advised has nothing to do with injectors.
Il advise one more time, your issue started after breaking a cam belt and the cam lobes turning on the shaft would be the best place to look for the cause of your issues.

The issues started after a "diagnostics" at the Volvo dealership where I got a car back that had no power and by the sound of it, a cylinder that was shut off. The belt had snapped months before, was replaced, verified and car was fully functional and fully drivable. Just barely noticable lack of power that was moslty due to the Soot filter being full, so the car reduced its power.

Even after being verified by a Volvo mechanic, the dealership also verified that timings are all in order and nothing seems wrong.

But anything goes, will also check your suggestions.

It wasn't my suggestion someone else on your thread suggested it. But it was my suspicion from the start. It needs looking at before you go further. It's been poked and probed over so many times according to your thread, but from what I read nobody has had the balls to remove the cam cover and actually look.

if its had a snapped cam belt its not unuseual for it to split or break the cam holding caps needs investigateing

What is the rail pressure during cranking?