Correcting a Mistaken Bracha

See Safek_Brachot_LeHaKel

Caught in Middle of a Mistaken Bracha

1. If it is caught after the word Baruch Atta just stop and that's fine.
2. If it is after Hashem say Lamdeni Chukecha. That isn't a bracha levatala but it isn't something to do initially.
3. If it is after Melech Haolam some say that there's a solution to complete the pasuk in Divrei Hayamim. See Safek Brachot LeHakel
4. If a bracha is made completely incorrectly one should recite Baruch Shem Kavod.

Quick Corrections: Toch Kedi Dibbur

1. If one said the wrong text of the bracha it can be fixed within Toch Kedi Dibbur.
2. If one said a correct bracha and finished one shouldn't fix or amend it within a Toch Kedi Dibbur and if one did so it is questionable if one's original bracha or one's emendation is effective.