Loss of performance on a diesel check turbocharger pipes has not blown off. See guide.
If cut-out and only showing less than 50 mile range assume out of fuel, add 10 litres and try restarting.
Flat battery can't get tailgate open. S60 etc. are fitted with electric tailgate which you can't get open to jump start when flat. What you need to do is open car with key and power car up though fuse box to open tailgate and then jump start in recommended way. To do this you will need a piece of cable fitted with an inline fuse. First with keys out of ignition switch connect the black jump lead (negative) to a suitable point on the body (door hinge, trim screw etc.) then connect your fuse wire to red jump lead(positive) be careful not to touch the car and then connect to the car though the end of a fuse (central locking etc.) there are two small openings in the end of each fuse, you can use either, then press button to open tailgate, if no luck try a different fuse, don't try to start car this way only open tailgate, then jump start car in recommended method.
If trouble removing key make sure fully in park (may have to press brake pedal)
If battery going flat check lights in the bottom of the doors are going out, the micro switches in the door catch fail, remove bulbs until repaired.
Use the advice links above to help diagnose your non-start, immobilizer, warning lights, and engine or general problems.