You are required to supply information in the sections marked with a grey checkmark (now a grey triangle with exclamation mark), in all required fields (marked with a blue asterisk). This includes, but isn't restricted to:
Pricing and Distribution:
- setting app availability to all countries (don't worry about this, read on),
- configuring presence of ads and being targeted primarily at children,
- confirming Android Content Guidelines compliance,
- acknowledging the app being subject to US export laws,
- configuring testing (you can have a closed alpha, hence countries doesn't matter at this stage)
- uploading feature graphics and even screenshots, yeah...
Once that's done, you'll get two "Ready to publish" labels, at the top of the page, the right one being a link to the App Releases management section where you can complete your rollout.
Yes, this is even more horrible UX than Google Play's previous light grey 'Why can't I publish?' help link on the top of the page. Make the best of it before the next iteration.=)