Same story.
Got the old 2.8.6 files from another site and overwrite the wp files under root one by one to see which files cause the blank page.
It turns out the wp-setting.php is the one that causes it to go blank. I look at the difference between 2 versions and there are many changes in the database.
Put the 2.8.6 version of the file over and the blog and admin loads fine but all the admin functions will error out because all the new files under /wp-admin/
I eventually use the 2.8.6 files to restore it back to 2.8.6 and will wait till the fix is out.
I have no problem with another site using auto upgrade feature.