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Do you get all other normal voltages, excepting CPU core?
Check if U7310/20 are correctly powered and look if R7311/21 and C7311/21 are all good/present.
Also check U7200 area, VR_ON, VIN, VDD.
Is sufficient one corroded small resistor; and there are many, too many...
You may also consider to change the MOSFETs from CPU power supply.
No use in measuring Vcore if there is not even fan spin. Check all S4/S3 rails first if present then all S0 rails. S0_CPU will be the very last rail to come on and the fan should spin first.