Xiaomi India — redmi note 5 pro booting problem

My wife's phone redmi note 5 pro all of a sudden not booting up. I read and checked in youtube videos its due to software problem so i shown that to mi service centre. There these people told that it's a motherboard issue and asked me to pay 5k if i have to go for motherboard replacement. After that i shown my mobile to two mobile repair shops there they told motherboard is fine it's a software issue that only mi people can fix that. I don't understand why these guys don't fix the software problem and asking for motherboard replacement.