Running a 3kw diesel heater was running before now E27 error

I did a bench test of my 3kw diesel heater to my Bluetti AC50s and it worked with no issues. Next day I did the final install and tried to test the unit again to make sure it was working properly after the install and now its showing an E27 code which to my understanding is an over current error. Not sure why all of a sudden its showing this error when starting the heater, anyone have any suggestions ? Thanks !

Measure how much watt the heater takes using a power meter when connected to utility power. If it is more than 300 watt you should not use with with your AC50s.

its just super strange it worked for me before with no issues and now its a problem, will definitely do a do a power test and see