It sounds like a bad connection that is being disturbed by the vibration of the steppers. I’d suggest a detailed inspection of all the connections. Make sure any connectors are seated completely, terminal screws are tight and things like that. These have a reputation for poor wiring practices, combine that with the long trip and things work loose quite frequently.
If nothing shows up that way, you may have to power on the laser and start gently tapping the control board, power supplies etc with a screwdriver handle while watching the meter. Make sure you are safe about it, and use an insulated tool, laser glasses and stay away from dangerous areas. Keep the cover down if possible. These don’t have interlocks and have plenty of voltage and laser energy to cause serious injury or death, so if you’re not sure you can do it safely, Don’t do it.
I’ve worked around dangerous machinery for years, but still hesitate to suggest to other people some of my methods. Banging around in an area with live HV and IR beams is not for the careless or uncertain person, so only proceed with that approach if you have the experience and are comfortable with the situation.
It looks like 90% of the circuitry can be accessed with the laser area closed. Start with the control board and power supply, your problem is likely there, and check the connections on the switches as well, they come loose in shipping often, which is likely the sort of problem you will find.
Good luck, and be safe.