Hi Mickey,

Get yourself the nice wiring diagram for your 2007 S80: TP 39100202
http://www.volvowiringdiagrams.com/?dir=volvo/S80%20Wiring%20Diagrams

There's an ajar switch in the door lock modules, but you said
later that the key only cycled the driver door lock, which means a problem
with Central door locking. There's a module "DDM" 3/126 in the drivers door that's a candidate to check out. One problem with things in the door is the
wires back to the car can get broken with being bent all the time so you can
easily have a broken wire in the door harness. This is not a fun job to fix.

My hunch: I'd verify that the hood latch switch is working with an ohmmeter
you can hook up an ohmmeter with the continuity alarm and shut the hood to make sure that you don't have to realign the switch and/or the switch actuator.

If you want to just silence the alarm look it up in the wiring diagram pg 87
it's called "SCM" Siren Ctrl Module item 16/35

Look on the left of the page for components, click the triangle to find
16/35 and you will move to a new page with a picture of what it looks like
and an arrow showing where it is.

It looks like it's in the engine bay mounted on the firewall in front of the
passenger then if you just want to disable the siren, you can try unplugging
the connector first, if that doesn't do it cut the red wire to the siren, that's the +12V so find a small wire nut for it and/or tape and tiewrap it up securely. (You found out that pulling F26 also kills Climate Control)

Good luck, Bill