Quality assurance process 1.Provide few pictures of the product to check the appearance (as the picture shows): Must be clearly enough to see there’s no damage and disassembly. 2.Provide the S/N picture of the product to check the guarantee valid period. 3.We arrange engineers to solve online in 48 hours. Besides, we have after-sales engineers in some countries which could provide door-to-door service. Thanks for all the help, we will check and reply with satisfactions.