I think Manchester United is gonna wake up and ended up going to the next round, they ahve luck on their side because the other two teams of the group asides of Bayern Munich are weak (Copenaghe and Galatasaray) if that were not the case they can be already more out than in.
I'm not sure about the waking up part for Manchester United for now. It was totally normal to see them losing to Bayern Munich first. They even resisted really well by scoring 3 goals as well. However that loss against Galatasaray wasn't as expected as that one. They are literally at the bottom of the group with 0 points now.
Maybe Copenhagen matches would be an opportunity for them to collect some decent amount of points. But for now it is difficult to predict how many points they can collect in those matches. Copenhagen might even steal points from them home. We have seen Copenhagen doing good against Bayern Munich home the last time.
I personally do not think Manchester United is actually going to finish in any kind of respectable position in the Champions League. They will be very lucky to actually finish in any kind of decent position in the English Premier League. Expecting anything from Manchester United in the Champions League is actually a dumb expectation in my opinion.
Yes, they do have a chance against Copenhagen. But the way they have been inconsistent, it is probably not a good idea to expect a win from them to be honest. There is nothing to be surprised if the match ends in a draw. And personally, I will not be surprised if they actually end up losing the match.