The custom redirect feature is incompatible with mobile devices. This is a known problem and (presumably) blogger is working on fixing it, but for now, if you have a custom redirect set up on your blog, people looking at it on their phones or tablets will see the error message: Too Many Redirects.
I spent a lot of time trying to figure out what the heck was wrong when I got this error, so I'm just putting this out there as a public service announcement: if you use the custom redirect setting in blogger, your blog will not load on mobile devices. Sorry to be the bearer of bad news.
Luckily, my client and I were able to figure something else out that worked for her, so all's well that ends well.