http://www.nbcnews.com/id/44280851/ns/technology_and_science-tech_and_gadgets/t/protect-your-electronics-power-outage-damage/
As the blackout ends, and the power turns back on, there can be a surge that will damage the electronics.
With the plummeting prices of LED HDTV's, it may not be worth the money to fix and older plasma set.