S80 T6 electrical/starting/alternator problems
 

I am considering buying a 2002 s80 T6 as is for $1200. Currently the car will not start. When you turn the ignition the car will crank but will not turn over. Is this a alternator problem? The current owner said they were driving the car when all of a sudden the power went out. He got a jump and it worked for about 10 more miles before running out of juice and needing to be jumped again. Now the car wont turn on even while being jumped, but everything electrical will work while being jumped. Does anybody have a clue what the problem could be?