How to turn-off disable (or turn on and enable) Drupal maintenance mode and status via phpMyAdmin / database
To turn-off or disable (and vice-versa, to turn on and enable) Drupal 7 maintenance mode via phpMyAdmin, enter an SQL command in the field under the SQL tab:
To set website into maintanance mode:
UPDATE `variable` SET `value`='1' WHERE 'name' = 'maintenance_mode'
Change 'value' to '0' to take site out of maintenance mode
Click Go to execute command.