How do I fix pin unlock screen showing blank letters and numbers?

[AC Question]

Device: Samsung Galaaxy S5 running latest update.

 

[B. Diddy]

Welcome to Android Central! Do you mean that the digits on the screen are replaced by different sized blocks? This has been mentioned a few times. You should still be able to tap in your PIN. Then reboot the phone, and see if the problem persists. If it does, then try wiping the cache partition: http://support.t-mobile.com/docs/DOC-10404