[Tannaton]

Ae he ^^ said you need to get the car plugged in to some Volvo diagnostic gear at a dealer or Indie. That does mean a small investment upfront but in all likelihood it will tell you exactly what the problem is, and how to fix it.

Volvo's have very good electronics with aircraft like levels of security and resilience, this works to the owners advantage whether the car is 1 or 15 years old. As you would expect - you cannot overcome the security systems by simply pulling a fuse.

The battery failing in the alarm siren is a common issue on older cars but it manifests as an "alarm service required" message on the dashboard, it does not cause the alarm to trigger.

Getting the codes read will save you a lot of time, any car will become a money pit if random poke and hope diagnosis is applied. I don't mean to sound unfriendly, but we see lots of new members with cars that are far harder to sort out that needs be because of previous owners or their mechanics trying to overcome symptoms rather than get to the root cause of the issue.