Someone said the closing Torah blessing instead of the opening one. What should he do?

Question

A person who is called for an aliyah L'Torah said the closing blessing (אשר נתן) instead of the opening one (אשר בחר). He did say Barchu. Assuming that the Torah reader has not begun reading, which of these should he do?

1. Repeat saying the correct opening blessing with Barchu. End with the usual closing blessing.
2. Same as 1 but without Barchu
3. Don't repeat anything for opening blessing. In place of the usual closing blessing, say the opening one.
4. Same as 3, but for the closing say the usual closing blessing.

If the reader began reading, which of choices 3 or 4 should he do?

Answer 1

The Mishna Berurah in siman 139 #16 makes a distinction between someone who started to finish the bracha by saying the name of Hashem in ברוך אתה ה׳ נותן התורה or not.

If he did not say Hashem's name of the finishing bracha yet, he stops and says אשר בחר בנו.

If he has already said that Shem Hashem, he finishes that bracha, the Torah is read, and afterwards he makes the bracha אשר בחר בנו.