Opening the incubator if they have not pipped is not a big deal. The problem with opening the incubator is, if they have pipped, it is possible to shrink-wrap them. If they have not pipped, you won't shrink-wrap them. If they had not pipped when you opened the incubator, don't worry about that. You did no harm.
A drop in temperature or a short spike is not a death sentence. It takes a while for the core temperature to change enough to harm the chick inside. But if that temperature was high enough for a long enough time, yes it could have caused serious harm. There are plenty of people on this forum that have experienced short spikes and gone on to good hatches. It's obviously not good, but not necessarily that bad. it just depends on how high that core temperature got and that depends both on the actual temperature and how long it was at that temperature.
What I suggest is that you wait until tomorrow. If you have not seen any movement, heard any peeps, or seen a pip by then, do the float test. Get a container of warm water, somewhere around 100 degrees but no hotter, and put the eggs in there. They should float. If they sink, well, they are not any good at this stage. But you are not just looking to see if they float. If there is a live chick inside, that egg will rock and move on its own. To do this test, you are going to let them settle and look for movement. If an egg moves on its own, put it back in the incubator because it has a chance. If it does not move on its own, it is no good.
I'm not trying to sugar coat this at all or just saying any of this just to make you feel better. You are still within the boundaries of possibly getting a good hatch. We'd all love for out eggs to hatch at exactly 21 days but it just does not always work that way. I understand your anxiety. I've been there. It does absolutely no good to freak out or panic. Being patient is the best thing you can do.