[Q] Notification LED not Working after Resurrecting from Sudden Death

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Has anyone ever experienced strange rare issue with notification LED not working in 4.1.2? I've been searching and digging around the web, but it seems that this issue is quite rare and I haven't found any solution that works.

The LED is on during charging, boot-up, power off and even diagnostic mode (*#0*#) but never lights up for any notification event no matter what I set in Display Settings.
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This issue started to occur after the phone got bricked by the recently infamous sudden death issue and Samsung replaced its circuit board and clean-installed the latest 4.1.2 (this is what they said). I would really appreciate if someone would come up with a possible workaround before I resort to returning it to Samsung again, because this LED notification is a crucial feature to me.

P.S.: LED was working fine in 4.1.1 before the sudden death. Phone was never rooted or modded, no backup/restore procedure was ever performed, except that built-in Google backup/restore.