Same thing happened here yesterday, only solution is a new tank? This is a 150 gallon and I haven’t ordered another tank. I have a spare 55 but it’s just a basic tank not reef ready, I have a lot of Coral and rock, what should be my first steps?
If it were mine, I'd throw the same type of clamps OP used,(Irwin bar clamps) careful not to over tighten, just snug enough to keep it from pulling away any farther, and contact manufacturer.
It's possible a new brace can be put on, but tank probably has to be drained.
Or you could take this time to just replace it, which would probably be my choice if budget allows.