Just installed New Motherboard but I can't hook up to Sprint Network

Title says it all, now that new mother board is installed I have no ability to hook up to Sprint's network although I sometimes have 3 or 4g and wifi with 3 bars of signal. What could be wrong? I spent an hour on the phone with Sprint with not resolution.

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Is the motherboard model number matching with the Antenna on the SIII display frame? E.g i9300 on i9300 and i9305 on i9305.

Mismatching ones can cause issues like this.

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