if not watching carefully may miss it, but payara do show signs, such as heavy breathing, lethargy, but when they become disorientated and loss of balance, usually don't recover.
if it wasnt the water change, could have gotten spooked and crashed into the glass, and knocked itself into that state. check for signs of this. that said, raphs are prob least prone to die from smashing their noses it. have seen a lot of raphs with essentially no nose, and have seen them heal from fight injuries that would have killed any other payara.
sorry to hear the news, hope it pulls thru, GL.