I have posted on threads that are saying they can’t restart... I am experiencing the same problem... I have downloaded the new update for Sierra but it just won’t restart....it sits there doing nothing for hours... my Macbook Pro is a 2013 model so it should be able to accept the update.... other threads have said they are having the same problem on iMac’s....... not got an answer for this problem at all..... please can you help me.. thanks.