I had exactly same problem but mine iPhone had repeating charging sound (every 5 second). Same thing, after screen replacement LCD went black and unresponsive. Mine problem was in one capacitor, it was under the close to the Wi-Fi chip. After removing shorted capacitor phone turned ON normally but power button and volume up/down doesn't work anymore.
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I had exactly same problem but mine iPhone had repeating charging sound (every 5 second). Same thing, after screen replacement LCD went black and unresponsive. Mine problem was in one capacitor, it was under the Shield, next to the Wi-Fi chip. After removing shorted capacitor phone turned ON normally but power button and volume up/down doesn't work anymore.
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My advice is to check capacitor if you have tried everything :)
I had exactly same problem but mine iPhone had repeating charging sound (every 5 second). Same thing, after screen replacement LCD went black and unresponsive. Mine problem was in one capacitor, it was under the close to the Wi-Fi chip. After removing shorted capacitor phone turned ON normally but power button and volume up/down doesn't work anymore.