Su-Kam — inverter showing overload indication during power cut

Address: H.No:29-1447/6, Road No:3, Kakatiya Nagar(West), Neredmet, Hyderabad, Andhra Pradesh, 500056

I have purchased model 850 va shiny inverter, on 29/6/2014, currently for past one month we are having issue with it, when ever power cut inverter is showing overload indication and power is tripping, we have forced to restart the db box.
Detail of the inverter
Model: model 850 va shiny
Code: fbdhupshsw012aa0085001
Request you to kindly assign technician to resolve the issue at the earliest.