Open phone, were welded on the display interface first, trouble still. Power on boot, test interface is the interface the PIN voltage with a multimeter, voltage is 0V found 18 feet, is not normal. Control wiring diagrams to find and was briefed on the feet from CPU to 4 feet. Detecting CPU 4 pin, voltage 2.75V normal. Due to judge between them disconnected, using a paint line connecting the feet of fly line, power on test machine, looks fine.ifkservice manual download site