@HollowTheNoobie
I have seen badly earthed and not-at-all-earthed speakers where voltage can be dumped on the audio connection causing damage to an output stage.
So it is possible.
Presuming you were connected to the headphone 1/4″ TRS Jack output, to troubleshoot, I would suggest switching the monitor output to ‘phones’, switching all ‘phones select’ switches out, so you should be hearing the main mix, and ensure you can get signal from the main outputs. Then connect the RCA monitor outputs to something and turn up the monitor level.
If you get something from the main and monitor output, but not the headphone output, it would suggest a hardware issue with just that output.
If you get something from main, but not headphones or monitor, it may be a switch or internal routing issue.
To get your ZED checked over and repaired if necessary, please contact your local distributor (https://www.allen-heath.com/community/distributors/).
Thanks,
Keith.