You can use a block explore to find out what specifically you did
@evernoticethat

The interesting thing about downvoting is that it is completely separate from up voting.
You have a different pool of vote power for each.

So, to fix downvote, you have to click downvote again (i believe)

When you reach 1,000,000 vests, you will be given a %-slider so you can adjust your votes. This gives you a two step click, which can give you time to fix errors.

Thanks for thinking of my blog.