9 times out of 10, the battery light is actually indicating a bad alternator.
However, it could have been a nad battery, that has taken OUT the alternator.
The older fords you could change out just one bad part of the charging system, but the newer fords are all contained inside the alternator. So even if its just the voltage regulator that took a crap, you have to replace the entire Alt.
Better get the bats checked while your at it and make sure they didnt go bad and smoke the alternator.
You say he has a 2000, so if he has STOCK original batteries, they are over 5 years old and should be replaced anywayz!