Read the manual.
That is the EXACT SYMPTOM of a failure of the safe sensors.
They do not need to be “reset”.
Make sure that they are clean. I have seen blowing leafs and pull rope block them.
And aligned. There is an LED on each one that should be lite if they are not blocked and aligned.
If not check the wiring for any loose connections or broken wires.
If this still does not fix it them you need to replace them.