Updated to Drupal 7.51 and website is now stuck in maintenance mode I just went to update Drupal 7.5 to 7.51 and fortunately the update worked. Unfortunately our site is now locked in maintenance mode and I was logged out of the system and cannot get back in as an admin or anything on the site for that matter.

We tried to do a site rewind to go back to our original settings before the update but still no luck. We also tried using /user and also /?q=user but this doesn't work either. The site seems to be stuck in some sort of page refresh loop. Does anyone have any suggestions of what else we should try or what we should do?
I am compiling here some points which I found. Following list I have ordered them from common to complex solution.

1. Clear cache:

First thing you can do is clear the cache. If you read the forum discussion on the Drupal forum page titled: Site stuck in maintenance mode!, you'll find various people solved this issue just by clearing the cache. 


Through Admin UI: As per this comment just clear the cache by going at Administration/configuration/performance. 
Using Drush: If you are using drush, you can do this by command drush cc all.
Other methods: If above both methods are not accessible for you, you can try other methods witch are listed in this article: [Drupal]Methods to clear Drupal caches


2. Login to site:

You can try some methods to login into site while still site in maintenance mode. 


Login to site using /user/login: On this question of DA: How can get my site out of maintenance mode? @Dmitry has stated in his answer,


  Just go to /user/login, it works even in maintenance mode, and then
  sign in as an admin.

On other Drupal forum QA also if you see the comment on this Link, it talks about using /user/login. I have pasted here,


  I just had a similar issue with a D7 site I was performing maintenance
  on. Logging in via http://example.com/user and
  http://example.com/?q=user wasn't working. What did, though, was
  http://example.com/user/login.



3. Changing Maintenance Mode setting:

@mixerowsky has very well explained various ways of changing the maintenance mode in his answer at this DA question: How can get my site out of maintenance mode?