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If you really get 12V_S0, then must have voltage on several coils.
Is more important to post them, instead of S5/4 voltages; S0 can't come on, if S5/4 are missing.
L7410/510 voltage must appear before CPU core.
In fact L7510 and CPU core voltage cannot appear without L7410 voltage.
So check U7400 basic voltages: pins 13, 14, 3.