If this hoist goes down when the up button is pressed this can be caused by one of the following issues.
Number one cause:
The phase of the electrical power has been reversed after the hoists have been installed. If you have other fixed speed hoists in the system do they do the same thing? Has there been electrical work done in your building, such as HVAC changes? If the answer is yes then you need to call the electrician to swap phases to the hoists.
Number two cause:
One of the three phases of power has dropped. Please call your electrician to test the power feed to the hoists.
Number three cause:
The contactor is not engaging all of the way.
Does cycling the power at the controller clear this?
Does cycling power at the breaker fix this?
If the answer is no, please call your local rigging dealer for service or ETC rigging support for help.