Issue with flickering on BlackBerry Passport screen temporarily halts BlackBerry 10.3.1 update
Clewley did mention in a tweet that BlackBerry is slowing down the speed of the update, and asked for patience from BlackBerry 10 users. Besides the Passport, other phones being updated include the BlackBerry Z30, BlackBerry Z10, BlackBerry Z3, BlackBerry Q10, BlackBerry Q5, Porsche Design P'9982 and the Porsche Design P'9983. The BlackBerry Classic comes with the new OS build pre-installed.
Besides the flickering screen on the BlackBerry Passport, Clewley also mentioned something about the low volume of ringtones on the BlackBerry Q10. He suggested that those with the device select override profile volume and then increase the volume. Hopefully your BlackBerry 10 handset updated to BlackBerry 10.3.1 without issue.