Mac Pro 6,1 (2013) will not turn on

[dickybow]

2013 Mac Pro that was working quite happily now fails to power on after changing the memory.

I have reinstalled the original memory and reset SMC = no improvement

The rear panel and power button illuminate for 20 seconds and extinguish.

No video ouput. No fan movement.

Please advise

 

[dickybow]

Left it without power for an hour, same

Dismantled and reassembled and it works !

Strange