Assalamou Alikom Warahmatou Allah,
There is no general consensus on this issue and there is no evidence from Qur'an and Sunnah that explicitly prohibits that a young boy leads Al'Salat.
In contrary, there is evidence toward that consisting in the Hadith narrated by Aamr Ibn-Salamah who lead Al'Salat when he was a 7 years Old boy.
Al-imam Al-Shafii allowed that especially if the boy knows well Qur'an and Sunnah better than anybody older than him.
Al-imam Malek disliked (even prohibited) that a boy leads Salat Al'Farida.
Concerning imam Abu Hanifa and Ahmad there is no general consensus on what they said about that.
And Allah knows best,
Wassalam