Opto 22 Snap pac S1 getting failed

We are facing issues with 2 no. Of snap pac S 1 controllers out of which one controller status led is blinking 4 times in red color as per the blink codes provided in the snap pac manual it is written invalid Mac address .
One controller is showing 1 time orange blinking and for both the controller even after pressing the reset button seems to have no effect on the status led.
We are not able ping the ip also and also not able to download the program.

Can you tell the probable causes of such failure so that we can eliminate such failure for other controllers installed in site.

Is it necessary to connect the ground terminal of the controllers.

Welcome to the forums.

Please get hold of our support team; https://www.opto22.com/support
They will be able to arrange to have the controllers returned to the factory for inspection.
Once we know more about whats failed we will be able to see if there is a common failure and what the next steps should be.