Make sure the car is in neutral (park for automatic)
Open the bonnet (hood)
You shall see a red coloured connector by the left hand side fuse board.
Connect the positive to the other vehicle, then connect the negative to the engine.
Always best to let the charge run for a couple of minutes, then start the XC90.
Leave both vehicles running for a few minutes to get the best charge to the battery.
DANGER:
Always connect the jumper cables to dead battery vehicle FIRST.
You may have unburnt fuel sitting in the engine, this can cause an explosion if a spark occurs from the cable connection.
ALWAYS check polarity of the cables are correct BEFORE connecting - this can cause a fire, or even a battery explosion if incorrectly connected.
Additional information will be required to answer your question. Is it an aftermarket back up camera and what year is the XC90?
The 2011 Volvo XC90 has 24 valves.
The 2012 Volvo XC90 has 24 valves.
The 2013 Volvo XC90 has 24 valves.
The 2006 Volvo XC90 has 20 valves.
The 2010 Volvo XC90 has 24 valves.
The 2007 Volvo XC90 has 24 valves.
The 2014 Volvo XC90 has 24 valves.
The 2008 Volvo XC90 has 24 valves.
The 2005 Volvo XC90 has 20 valves.
The 2009 Volvo XC90 has 24 valves.
The 2004 Volvo XC90 has 20 valves.