unroot Bionic help needed

I have been helping an online friend who is trying to unroot their Bionic so they can get back onto the OTA path. Their English is not so good. Besides using RSD Lite, is there a way to remove root on the Bionic? He is rooted on .902. For some reason his phone will not take the OTA or does not see the OTA. And I have no idea how he rooted.

Rsd easiest way. 20 min of time and its done.

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Root in itself wont stop ota. Custom roms and changing the ne of the updater will do it.

Prior to taking ota need to make sure stock and bloated

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