We see the confusion, in Blogger Help Forum: Get Help with an Issue.
The addresses were right - and all the DNS servers updated correctly. But when I open the website, it does not open. It continuously reloads for 5 minutes and after 5 minutes it shows an error.It's frustrating, when everything is setup properly - but still no results.
It's also frustrating, when you forget about unsupported tweaks that you made, to the blog - then have to ask for help.
Whenever changing the URL, check for - and remove - any redirecting scripts.
Before you publish a blog to a new URL, you need to check the template, for any redirecting scripts, that you may have previously installed.
Scripts which redirect - or block redirecting, when the blog is published to BlogSpot - will not work for you, when you publish to a non BlogSpot URL.
You will need to connect URLs, when possible - without scripts interfering.
Any time you change the URL of the blog, you're going to need some ability to link from the old URL to the new URL. Before you change the URL - either BlogSpot to BlogSpot, or BlogSpot to custom domain - check the template, for redirecting scripts.
Any redirecting scripts, that might have helped you with the blog originally published, will be a problem, when you change the URL. Remove any scripts, before changing the URL.
Better yet, don't add redirecting scripts. If you got this far, without having the blog classified as a malware host, consider yourself lucky.
Some blog owners install mysterious scripts, to "protect" against unwanted Blogger features - and forget about their unwise tweaks. When they change the URL of the blog - and the blog, under the new URL reacts to the previously installed tweaks - they are clueless.
If you make unsupported tweaks to your blog, only you can correct problems that arise, later.