Cannot unlock K2LE

It happened now fourth time! I cannot unlock my K2LE. Press fingerprint sensor, asks for PIN (which it does sometimes for security so I just thought it is that). PIN entered, but I get black screen, navigation buttons lit. After 5 seconds, opens lock screen (just like pressed power button). Again, fingerprint or swipe up from bottom = asks for PIN.
This time, I have picture pattern for unlock, but it asks for PIN either. If I put bad PIN, it says Wrong PIN and substract try count from 10 to 9. I have to reboot the phone.

This phone really hates me :(. I have not done any upgrade and all automatic updates are disabled..

Originally Posted by skkayman

It happened now fourth time! I cannot unlock my K2LE. Press fingerprint sensor, asks for PIN (which it does sometimes for security so I just thought it is that). PIN entered, but I get black screen, navigation buttons lit. After 5 seconds, opens lock screen (just like pressed power button). Again, fingerprint or swipe up from bottom = asks for PIN.
This time, I have picture pattern for unlock, but it asks for PIN either. If I put bad PIN, it says Wrong PIN and substract try count from 10 to 9. I have to reboot the phone.

This phone really hates me :(. I have not done any upgrade and all automatic updates are disabled..

Ok, disable all pin/password/pattern/fingerprints and start over, see if that helps.

By the way, you can uncheck the option "power button instantly locks device" and put something like a 1 or 2 minute delay to lock the device.
Meaning if you press the power button or just wait till the screen shuts off, it'll take 1 or 2 minutes to actually lock the device. If you press the power button before then, you'll still be in the home screen.

You can also do the MMI test (enter *#2886# on the phone Dialer, must be using stock phone app) to see if the actual fingerprint sensor is fine.

MMI test is OK. Fingerprint sensor works great, it just seems that it is software problem. I can try disable all security (even now anyone can enable flight mode, change volume, enable bluetooth, enable mobile data without unlocking! :( ) and see what happens. But this occurs randomly every few weeks so I won't know until it happens again and that might not be soon :).