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Phone works but screen fades to black during boot.

I was changing the two touch ICs when I accidentally bumped U5302_RF out of place.

I removed it and tried to reseat it, but I did not reball. I don't have any new spares to try.

Now when you turn the phone on it shows the Apple logo for about 5 seconds and then it fades to black. Backlight remains on.

I see U5302_RF is a "LCD Boost" chip. Is it likely that this chip is the cause of the problem? I have a new one on the way but just wanted some opinions.

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This is a belated answer so hopefully it can be of use to folks who search for and find this question.

U5302_RF is the Stockholm IC, responsible for NFC functions. Whenever an IC gets dislodged while performing a repair, it’s important to remove it, reball it and the install it properly to insure there are no bridges underneath the IC which could cause shorts.

As for the OP’s particular problem, the dark screen may be caused by an improper reballing of the Touch IC’s or collateral damage elsewhere in the area due to excess heat during the repair attempt. The various small components surrounding the Touch IC’s, as well as the components on the opposite side of the board (corresponding to the connector area), are all susceptible.

Finally, when doing a Touch IC repair, it’s critical to run a micro-jumper on the M1 pad otherwise the repair will be a short term fix only.

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