I've had an Eotech 516 fail on my before... well not exactly failed, the nitrogen purged mid range session and the reticle dimmed dramatically. Wasn't a catastrophic failure as I could still kind of see the reticle.
...Slow, deep breath in followed by two quick, shallow exhales, then one long breath out. It should sound like "HEE HEE HOOOOOOOOooooooo...HEE HEE HOOOOOOOOooooooo". Once your comfortable with that breathing pattern, try to sync the tempo up with your heart rate. "Lub-dub...HEE HEE HOOOOOOOOooooooo... etc". ~ CBruce