It might be possible that the Russians tried to release a lot of water to hamper Ukrainian crossings, but then a magnetic mine got sucked into an intake, and did not detonate until it was inside near metal components, causing unintended secondary detonation of the main charges that the Russians had emplaced inside.
I do not propose that they be given the benefit of the doubt. Russia planted the charges, the mines, and manipulated the water levels and flows. They must be held accountable. Otherwise, there is no deterrent against them blowing the Zaporizhzhia Nuclear Power Plant (ZPNN).
It seems more likely to have been a deliberate demolition by the Russian chain of command, in which case they are all the more likely to continue that scorched earth strategy with ZPNN, as they are forced to withdraw.
but then a magnetic mine got sucked into an intake
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A mine, capable of blowing up a tank or a mine that could hole a ship, would only scratch a dam. Explosives need to be in the tons to do the damage they did.
In any case, everyone seems to overlook that the hydroelectric power plant with the turbines was also blown up - no mine there.
The Russians are the stupid ones the blew the dam and the station up, and like Chernobyl & their pipelines, they will try to do something even more stupid with the rector complex they hold.