On my EMS760 I have to have the washer/dryer breaker on for the display to work, not sure if impacts the operation of the EMS though.
You can try to do a complete reset by shutting off all AC & DC power, pulling the fuse, wait ~10 minutes.
If that doesn't work you may have a bigger problem. Contact M&M Electronics in Ohio https://www.mmrvelectronics.com/
They can walk you through more trouble shooting. I had to do this and found my board was bad and had to upgrade/replace with a new board and load monitor. They overnighted me the parts to the destination I was traveling to, good group to work with & support.
If you are electrically inclined you may be able to bypass the EMS board by simply taking the 2 wires out of each realy and wiring nutting them together. I did this to get one AC unit working until I got my new board. You can bypass all the relays but then will have to control power to below 30 amp if plugged into that size hookup. Take pictures, make a wiring diagram, and put labels on the wires before you start.