I have almost exactly the same problem. Today I left the phone charging overnight and in the morning the notification LED was bright blue. It stayed this way after I opened and read all texts and mails, it stayed regardless if the screen was on or off, it even stayed when I turned the phone off(!) and I only managed to put it out by pulling the battery - however it went back on immediately after replacing the battery. I turned off all notifications in settings, made sure I have plenty of free memory and card space etc. etc. The only thing I managed to do was to make it dim blue instead of bright blue after shutting down and booting up again. Now it lurks in the darkness, occasionally flashing, but mostly just glowing in blue.
The only ideas that I have left:
- some app update brought an unsolicited feature, but how to check it w/o wiping up everything? and how the hell does it stay lit after turning off the phone anyway?
- something went bad when charging - but these phones are supposed to have some protections from overcharging, so it shouldn't be a problem if it stays connected at 100%, right? besides, the phone works perfectly normal otherwise.
- I'm using an s-view cover, maybe it has something to do with it? I tried removing it to no avail - but maybe the magnets embedded in the cover contributed over time to the now-observed led malfunction?
- do you use S-view? from what I understand, your problem also occurred after charging - did the phone stay on charger for long, eg. overnight? maybe you managed to solve the problem since?