You guys probably have done this but though I'd discuss it more since it may happen to others.
With the Pocono off for 3-4 days due to warm weather, the flue started to backdraft, this happen with the old wood stove when it was rainy like today so I tried my old trick and it worked.
Took a plywood piece that fit over the ash door, cut two 2.5" holes in it and attached an old 130 cfm dual blower on the wood centered over the two cut holes, put a piece of foil over the baro, put the board up against the open ash door frame and left it there for a couple minutes and blam, flow was reversed, then put a 1200 watt heater in to bottom for 10 minutes, stack temp went to 90 deg, draft was .02 and start up was a beautiful thing. Always remove the foil before start up.
Don't let reverse draft stop you.
Fur what it is worth.