I have checked the database credentials and they are correct. I have other accounts/sites on Siteground and I just experienced the same issue in another account. I have restarted my browser and cleared my browser cache.
I checked with Siteground and they checked the databases and the user and can confirm that the user is added to both with full privileges so it won't be that.
This is the debug info provided:
/home/customer/www/dev4jt4a3.com/public_html/installation/src/Framework/Database/AbstractRestore.php:973
Cannot connect to the database: one or more of the database host name, user name and password you have provided is incorrect.
/home/customer/www/dev4jt4a3.com/public_html/installation/src/Framework/Database/Restore/AbstractMySQLRestore.php:91
#0 /home/customer/www/dev4jt4a3.com/public_html/installation/src/Framework/Database/Restore/AbstractMySQLRestore.php(57): Akeeba\BRS\Framework\Database\Restore\AbstractMySQLRestore->getDatabase()
#1 /home/customer/www/dev4jt4a3.com/public_html/installation/src/Framework/Database/Factory.php(96): Akeeba\BRS\Framework\Database\Restore\AbstractMySQLRestore->__construct(Object(Akeeba\BRS\Framework\Container\Container), 'site', Array)
#2 /home/customer/www/dev4jt4a3.com/public_html/installation/src/Controller/Dbrestore.php(67): Akeeba\BRS\Framework\Database\Factory->restore('site', Array)
#3 /home/customer/www/dev4jt4a3.com/public_html/installation/src/Framework/Mvc/Controller.php(188): Akeeba\BRS\Controller\Dbrestore->start()
#4 /home/customer/www/dev4jt4a3.com/public_html/installation/src/Framework/Dispatcher/Dispatcher.php(61): Akeeba\BRS\Framework\Mvc\Controller->execute('start')
#5 /home/customer/www/dev4jt4a3.com/public_html/installation/src/Framework/Application/AbstractApplication.php(82): Akeeba\BRS\Framework\Dispatcher\Dispatcher->dispatch()
#6 /home/customer/www/dev4jt4a3.com/public_html/installation/index.php(103): Akeeba\BRS\Framework\Application\AbstractApplication->dispatch()
#7 {main}
#0 /home/customer/www/dev4jt4a3.com/public_html/installation/src/Framework/Database/Restore/AbstractMySQLRestore.php(82): Akeeba\BRS\Framework\Database\AbstractRestore->getDatabase(false)
#1 /home/customer/www/dev4jt4a3.com/public_html/installation/src/Framework/Database/Restore/AbstractMySQLRestore.php(57): Akeeba\BRS\Framework\Database\Restore\AbstractMySQLRestore->getDatabase()
#2 /home/customer/www/dev4jt4a3.com/public_html/installation/src/Framework/Database/Factory.php(96): Akeeba\BRS\Framework\Database\Restore\AbstractMySQLRestore->__construct(Object(Akeeba\BRS\Framework\Container\Container), 'site', Array)
#3 /home/customer/www/dev4jt4a3.com/public_html/installation/src/Controller/Dbrestore.php(67): Akeeba\BRS\Framework\Database\Factory->restore('site', Array)
#4 /home/customer/www/dev4jt4a3.com/public_html/installation/src/Framework/Mvc/Controller.php(188): Akeeba\BRS\Controller\Dbrestore->start()
#5 /home/customer/www/dev4jt4a3.com/public_html/installation/src/Framework/Dispatcher/Dispatcher.php(61): Akeeba\BRS\Framework\Mvc\Controller->execute('start')
#6 /home/customer/www/dev4jt4a3.com/public_html/installation/src/Framework/Application/AbstractApplication.php(82): Akeeba\BRS\Framework\Dispatcher\Dispatcher->dispatch()
#7 /home/customer/www/dev4jt4a3.com/public_html/installation/index.php(103): Akeeba\BRS\Framework\Application\AbstractApplication->dispatch()
#8 {main}
Can you help?