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Iphone 6s no boot

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  • Iphone 6s no boot

    Hello everyone,

    I have an iphone 6s that shut off on the customer's hands a few days ago. the battery is fully charged and it does recharge a battery when plugged in. I have checked for a short on vcc main and there is nothing there. I plugged it in to my power supply and it doesnt draw any power when off. I checked for heat with alcohol and noticed that the alcohol around u4000 (chestnut) is evaporating much faster than the rest of the components. after checking the schematics i noticed that PP6V0_LCM_BOOST is shorted. Both C4007 and C4008 are shorted to ground. my question is would this cause the phone not to boot and also would i be replacing chestnut or is there something else on that line that i need to check to find a short. I dont want to replace chestnut unless i absolutley need to.

    Thank you!

  • #2
    What makes you think this phone isn't booting? If you have a short on lcm boost, and the phone is charging, then the most likely case is that the phone IS booting, but has no image. If you put the phone on dc power supply and see a normal appearing current consumption, then the phone is booting.

    Find and clear the lcm boost short (assuming that you think it is short because your MULTIMETER shows a low resistance to ground on this line, not just because you have 0v on the line)
    You know that you won't have image with an lcm boost short, so solve that first. You will not really be able to tell if the phone is booting or not until you have image again if current consumption on DCPS appears normal. A phone on iOS12 will not be detected by iTunes without passcode, so we can't use that as a tool to see if the phone is actually booting anymore.