Stock Nexus 7 2013 stuck at "Google" when booting
OH!! Unexpectedly now it works!! Here's roughly what I did:


Flash 5.1.1, &amp; leave it to try to do normal boot => failed 
try to go to recovery => failed
flash 5.1.0, &amp; leave it to try to do normal boot => failed
try to go to recovery => failed
flash 5.1.1, &amp; leave it to try to do normal boot => success! but very slow process!


make sure when flashing stock images all steps are successful in the command line, e.g. formatting, updating (some missing .sig files are okay)