Assalamu Alaykum wa rahmatu Allahi taala wa barakatuh,
The question is about the word where Hamzatul wasl is followed by a Hamzatul Qat’. When we start at that word we say “eetuni” So the Hamzatul wasl will have a kasra, and therefore the Hamzatul qat’ will become a ي.
My question is why (when we start at that word) does the Hamzatul Wasl get a Kasra even though the third letter of the word has a Dhamma ? Baraka Allahu fikoum and I apologize once again.
Wa alikom asslam wa rahmatu Allahi taala wa barakatuh,
When the third letter is kasra or fatha, hamza Wasl will get kasra. This is indeed the rule.
The verb ائتُوني is not the original form of the verb. Instead, it was ائتِيوني with kasra under the ت and followed by the ي , but because there would be two vowels following one another, and to make the verb easier to pronounce, the ي was removed from the verb.The result is that now the ت instead of having kasra (the original state), it now has dammah ائتُوني since it is now followed by the vowel و. Therefore, when we place the kasra of the hamza wasl, because we depended on the original state of the verb. So, we choose kasra.
I recommend using this infographic https://arabic101.org/product/hamza-al-wasl-infographic/
It will help you in shaa Allah, and it is available for free.
Allah knows best.