So, my friend owns a 2006 Murano. The key FOB won't do anything, won't unlock the doors. Car says 'key not recognised'.
Which sounds it's probably a dead FOB or FOB battery.
Except the real key won't start the car either. It doesn't do anything. No start, no crank, nothing.
So, after charging the problem appeared to be the starter. Replaced the starter, charged it. Car started.
After a few minutes i removed the jump cables and it died within 2 minutes and the alternator started smoking a bit.
I found that on of the connectors on the alternator had been cut and spliced back together. These wires were touching and slightly melted where they'd been touching.
I seperated them, recharged and restarted the car. It was again fine until i disconnected the jumper cables. Again, it quickly died and started smoking again. This lead me to believe that it was a grounding problem and that it may be ok as long as the ground jump leads were connected. Started charging again and the alternator caught fire. So at this point a problem internal to the alternator, maybe. Kinda stuck at this point.
If you're not familiar with the electrical and charging system of the Murano, I'd suggestion getting the vehicle towed to a repair shop to have it looked at. Alternator catching fire sounds serious. I would do that before it causes any more damages to the Murano, especially to the electrical system which is quite sensitive. Just my 2 humble cents.