Is the Imam's recitation of "uhdina" considered to alter the meaning, and what is the ruling on the prayer of those led by him?

Scholars have differed regarding one who recites "ihdina" (إهدنا) with a fatha on the hamza or a damma on it. Is this a deviation that alters the meaning and invalidates the prayer, even if unintended, or not? And should the Imam correct his recitation, or should he not lead the prayer? The more cautious approach is to repeat the prayer that was performed behind him with this deviation.