as the above post, make a check list and check several things:
- reset, setup again the configuration as it’s lost after the reset
- if overclocked, turn it back to factory settings
- check the fan connection/connectors
- check the connectors to the hashboards.
- replace the PSU with a working one, often the PSU is the problem, smolten connectors, whatever.
in case you have more than 1x Z9, try replacing the hashboards from another Z9 to see excluse a vaulty hashboard as the reason.
And make sure you are indeed not overheating the unit and/or electricity circuit is stable and not overloaded.