If mobile not showing sim or show insert sim card you will do wph(wash,pest & hit) then check sim tray bye the multi meter
It will basically used to Nokia,Samsung,Sony,htc and other branded mobile phones.
If u follow this image you will solve any mobile phones insert sim or no sim problems easily.
description:- in sim tray have 6 legs ground,v cc,open,data,clk & rst.ground and vcc connect to the capacitor you should check capacitor if it short of damage it should be replaced or remove. data,clk & rst connect to the sim ic like as picture.if connection break sim legs to sim IC make a jumper like picture
If there is no sim ic there use resistor as a sim ic.if there is resistor change it or jumper it.if the problem not solve then heat cpu because sim IC linked directly cpu.Your problem will solved.
In chines board there is no sim ics.There used resistor and direct connect to the cpu.but some chines mobile board have a sim ics if there is sim ic then change that ic.