I believe the caveat here is that once either particle is observed, both are "constantized" into their final states (and manual changes to either no longer affe

I believe the caveat here is that once either particle is observed, both are "constantized" into their final states (and manual changes to either no longer affects the other). For example, until you look at your coin, it could either be heads or tails (and your friend's coin could also be tails or heads). Once you look at it and see that it's heads, it'll forever be heads -- and your friend's coin will forever be tails, regardless of whether they look at their coin when it arrives. The opposite is true: if you don't look at your coin and your friend does, then tells you his coin is tails, you can know your coin is heads. You can't change it to be tails and tell your friend he must've seen wrong -- his is still tails and yours is still heads. Obviously that's a super-simplified version (because I don't understand it all myself), but the gist is: once either entangled particle is observed, the bond between the two is broken and any manual modification of your coin (like flipping it over manually) no longer has any effect on your friend's coin, or vice versa.