This usually happens when PrestaShop can’t properly create or keep a session, so even though your login details are correct, it just refreshes the page instead of logging you in. Since you’ve already cleared browser cache and checked logs, I’d focus on server-side issues. First, manually clear the PrestaShop cache from the server (not just the browser). Delete the contents inside the var/cache/prod and var/cache/dev folders, then try again. Next, check your shop URL settings in Shop Parameters → Traffic & SEO. Make sure the domain is exactly correct — no mismatch between www and non-www, and no conflict between HTTP and HTTPS. Even a small mismatch can cause a login loop. Also make sure:
The PHP session path is writable. File permissions are correct. If you’re using Cloudflare or a proxy, it’s not blocking or altering cookies.
If this started after migrating the site or changing SSL, it’s very likely a domain or cookie configuration issue.