03 V70 shredded serpentine, bad alternator next, next day...

[guest]

I have a 2003 V70 2.4T auto with 22K miles. Two weeks ago the serpentine belt started to shred-replaced by dumbfounded dealer-says its a bad belt. They said the tension, pulleys were fine and no damage done. Two weeks later the battery is going dead (no warning lights ), took back to dealer and the alternator was bad (putting out 40), dealer replaced-says a bad alternator- that belt tension was fine-they think it was a internal short in the alternator-and were sending in to Volvo. It had been idling rough and had a rotten egg exhaust smell. The next day after it was fixed when started the check engine light comes on and blinks a few minutes then goes off (never blinked or stayed on that long before) Is this related to the work just done?