Happy new year TY, I think I may have found a step toward a diagnoses.
The attached picture shows points of continuity between 5v pin and ground when the new Arduino is attached with out power..
The strange thing is while testing voltages again I hadn't fully seated the Arduino on the top row of pins.
When I powered it up i got the test cycle of the RGB lights for the first time and the arduino never got hot it done the test correctly.
I then tested the voltage with the Arduino attached correctly (fully seated) and powered it up, I got 5v volts on the meter between the 5v Pin and ground on the clock board and Arduino got hot.
I eased off the top left side of the Auduino again, and again nothing got hot and the led test cycle worked ok so I'm thinking the short is to do with the ground pin on the top row of pins marked in red.
With Auduino attached fully all red 5v and ground points in picture have continuity.
With the Arduino not fully seated along the top row of pins 5V to ground.has No continuity
Powered up and Aarduino not fully seated I'm getting,
VIN pin to ground reads 9v
5v pin to ground reads 5v
and VCC to ground reads 5v
I would really value your opinion on these results and if i could be on the right track?
Tony