Generally, this follows reports by blog owners, that their readers are being redirected to unexpected and unwanted blogs and websites, from their blogs. Sometimes, we get the reply
I can't remove the code. Every time I login to Blogger, I am redirected, just as my readers are being treated!
When we see the latter complaint, we recognise yet one more blog owner who does not know how to properly protect himself, from malicious code and websites. Most people, who know about Layered Security, know that proper browser security is an essential complement to a properly chosen and maintained anti malware filter.
Many people, who care about browser based security, use Firefox with NoScript.
This combination provides Unix level security, "deny by default, permit by exception". Simply install NoScript as an add-on, to Firefox, to get started. Alternately, you may use Chrome with ScriptSafe, or Opera with NotScripts.
When using your browser with a script filter, there will be specific Blogger / Google websites which you should trust, and others which you should not trust.
Every time you surf to a different website - and decide that the owners of the website, which you are now viewing, have your best interests in mind - configure NoScript to allow that website, to display properly on your computer. When you find that a trusted host website does not display properly, examine the NoScript taskbar and the list of websites used by the host website. Look at the NoScript Options menu, carefully. Allow specific websites which you trust, and Forbid all other websites which you do not trust.
Deciding which websites to trust, based on their presence in the NoScript Options menu, will be a learning experience for a while. For some host website pages, which use a large number of unfamiliar websites, you may have to carefully select to "Temporarily allow all this page" - or you can "Temporarily allow" each single website, one by one, until the host website page displays properly.
When you decide to (permanently) "Allow" any website, that website will be "Allowed" on all other host websites where you may surf. Conversely, any website which you never select to "Allow" - such as the problem website which is providing the misbehaving code - will never execute on your computer again. This will prevent redirection on your computer, allow you to safely use the Blogger dashboard, and edit or remove any dodgy code which may be part of your blog.
After removing any dodgy code from your blog, always clear cache and restart Firefox, to test the effects of your editing.