On a fresh tinyG (no parameters changed), You should see happen when sending G code:
> M8 – turn Coolant LED on
> M9 – turn Coolant LED off
> M3 S10000 – turn SpOn LED on and PWM LED on
> M5 – turn SpON LED and PWM LED off
PWM probably won’t turn off.
Send $p1pof = 0.0 to change the off state phase of PWM to 0.0
Then reset tinyG with reset button (sometimes required for the $p1pof parameter to be re-read)
Retry M3 S10000, then M5
PWM LED now Turn on, Then off?
SpOn(and Spin terminal) still stuck off on staying at 0.7V max?
That sounds like a defective port output.
Anything connected to the Spin port terminal?