Unable to Power 8 Ch. Relay Board

[LarryD]

@mynameisaiden

The voltage across the negative and positive leads of my 5V 10A PS is 4 something, and it's sparking, so it's pumping.

This is not good, should be 5v, sparking is bad, you must have a short.
Fix this before you go further.

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4.7v on the relay Vcc terminal to Arduino GND is fine.

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What happens when you take an INx terminal to ARDUINO GND .