If you get a Recaptcha failed, the problem is that probably Google Recaptcha sees you as a bot.
First of all, check that Recaptcha logo appears in the lower right.
Try to login “slowly”, by manually typing username, then password; now make a pause of some seconds before clicking on login.
If you get this error again, try again, but even slower: make sure you cannot be misunderstood as a bot
trying to get into your account by brute force.
Do not keep trying, if it fails several times, otherwise you will be blocked altogether by the system (“ops, this is an error” will be displayed).
Make sure also to not have browser plugins that may interfere with google Recaptcha.
As soon as google Recaptcha has understood you are not a bot, you should be able to log in easily from now on. If it goes back to “Recaptcha failed” after a while, it may be a sign someone else is trying to enter into your login.