Analysis: DC Input PV1 voltage low.  DC Input PV2 voltage low
1. If it only happened in a bad weather (such as: in the evening or morning); but it’s normal at other times, so the failure probably be caused by the insufficient input power, this case is a normal phenomenon; Just wait for weather becoming better, the machine will automatically recover and generate power again, please ignore this situation.
2.Disconnect both of AC side and DC side switch, and unplug the Solar panel string from inverter one by one, to  check if the positive and negative of each string is wrong or opposite, and test if each string voltage is within inverter rated range.If the DC connection is correct, please restart the inverter and observe whether the inverter can normally return to work. 
3.Check if the inverter running mode be set correctly.
4.To exchange the 2 MPPT panel string and keep a further observation.