Warning! This is not good news for a 1 year old pool
The first thing to do is drain the pool down past the shallow end and cut out a big chunk of the new deck
Dig out the seam and the brace and at least 1/2 way down both panels. Knowing that you have a brace there is good news (what I suspect happened is that the brace broke - the ones we use have a threaded rod welded to the brace for adjustments - the weld probably popped) as long as the brace is still in the collar a new one can be attached to it without having to break up the collar to install a whole new one. Now it's just a matter of getting the walls back straight and securing them (the coping may have to be removed) - brute force is the usual method, beat the panels back straight
The fact that you have a liner in the way complicates things some, but not much - that's why we had to drain the pool, so the liner could be untucked while we pound on the seam - the only good thing about your pool being so new is that the liner can easily be reset
All that's left is to backfill the hole, reset the liner and wait for the ground to compact enough to repour that section of deck - unfortunately, it will always show as a patched section of deck :x , there is no way I know of to match up new crete with old, you can age the new crete with acid to make it look older than it is, but getting it to exactly match the existing stuff isn't going to happen (though with modern technology, someone out there might be a concrete aging artist and be able to do it)
It sucks to have to do this to a new pool! It's labor intensive and will never look quite right, but it beats having the pool collapse!
Let us know what the PB says, maybe he knows a couple of tricks I don't and it won't be that bad