Sorry to hear it didn't work out. I stopped cooking at the really low temps a while ago, I go 250-275 at a minimum now. Well, I should preface that by saying I'll set the FEC at 180 for a few hours for some extra smoke first then crank it up. Since you're cooking on an electric, just go to at least 250 straight away.
I'm thinking the main problem was the multiple power outages. For the first part of the cook, you're just looking to get the smoke flavor on the meat. 2 hours, 3 hours, 5 hours, whatever you think is the right amount. I think the 170 number is just a ballpark.
For pulled beef, I've switched to a recipe called Pepper Stout Beef. Since your roast is sitting in the fridge, it'll be perfect. For part two, slice up some onions, peppers, add some stout or porter beer. Or any beer, or if you don't do alcohol, beef broth works as well. Throw the roast on top, foil it and into the oven at 350 for about 3 hours or so. Since yours will be cold, add an extra hour. It's done when you can stick a fork in it and twist it like spaghetti.
Here's one on my cooks: https://forum.cookshack.com/to...cs-pepper-stout-beef
And the original recipe: http://www.thewolfepit.com/200...pper-stout-beef.html
Let us know how it turns out.