I am hoping someone here can help with some troubleshooting. While driving in Chicago I90 traffic, I heard a screeching/static noise from under the hood or through the speakers, and the "voltage overload" warning message suddenly came on followed by the battery light and a "power system service urgent" message. It was nighttime and the battery died after driving about 30 more minutes. This week my mechanic installed a new alternator and he said it's working, but the power system service warning and battery light came back on. He's stumped and suggested pulling out the re-manufactured alternator that I bought and replacing it with a new Volvo OEM or Bocsh. He also mentioned that it was possible that some gauges could have been damaged due to a voltage surge, perhaps explaining why the power system service light came back on. If anyone here has any experience with this issue or knows some reasons why these lights would be on despite a functioning alternator, please help! Thanks.