From what hole did he send his hand?
Rashi: It is the hole near the door 1 . I saw his hand, and my innards were reversed to return to love him, and open for him.
Rashi (6, according to the metaphor): When I did not open for Him and repent from idolatry, He showed His vengeance in the days of Achaz, and brought Melech Aram's army against him - "va'Yaku Vo va'Yishvu Mimenu Shivyah Gedolah...; va'Yaharog bi'Yhudah Me'ah v'Esrim Elef b'Yom Echad" (Divrei ha'Yamim II, 28:5-6).
Seforno: In the early days, in the days of Rechav'am, He sent His hand via Shishak, to make them repent - "v'Yad'u Avodasi va'Avodas Mamlachos ha'Aratzos" (Divrei ha'Yamim II, 12:8).
Malbim (Melitzah): Sending His hand is Nevu'ah - "va'Yishlach Hashem Es Yado va'Yaga Al Pi" (Yirmeyah 1:9), "v'Hinei Yad Sheluchah Elai" (Yechezkel 2:9). Nevu'ah came to him via the hole. I.e. He did not enter her room to be isolated with her face to face and to bring her out to Him, like the previous times. Rather, He informed her the matter of His Nevu'ah, which was full of rebuke and punishments.
Malbim (Mashal): It was in order to open the lock.
Why does it say "u'Me'ai Hamu Alav"?
Rashi: Refer to 5:4:1:1.
Rashi (6, according to the metaphor): [Achaz'] son Chizkiyah repented with all his heart to seek Hashem. All his generation were complete. They checked from Dan to Be'er-Sheva, and did not find an ignoramus; they checked all of Yehudah and did not find a man or woman [or boy or girl] who was not fluent in the laws of Tum'ah and Taharah. (Sanhedrin 94b). Also about Yoshiyah, it says "v'Chamohu Lo Hayah Lefanav Melech [Asher Shav El Hashem b'Chol Levavo uv'Chol Nafsho]" (Melachim II, 23:25), for he saw the punishment that came against Menasheh and Amon.
Seforno: Then they repented - "uv'Hikan'o Shav Mimenu Af Hashem" (Divrei ha'Yamim II, 12:12).
Malbim (Melitzah): She began to regret her deeds, and desire "k'Yarchei Kedem; ... b'Sod Eloka Alei Ahali" (Iyov 29:2, 4 - like days of old).
