I've had this happen a few times over the years. Usually it's a plugin that goes haywire. I've disabled all the plugins and still I can't access wp-admin.php - When I try I get
Error 310 (net::ERR_TOO_MANY_REDIRECTS): There were too many redirects.
When I try wp-login.php it will shows login screen, but won't log-in (goes into redirect loop finally landing on /wp-admin/ which is, as stated about the redirect errors.
Interesting enough, when I log in via the Android app I get right in and can edit posts, etc. That's how I'm going to upload my post tonight. :)
Is there something I can do via phpMyAdmin or ftp that could potentially fix this?
Again, I disabled all plugins and nothing changed.