What is the cost of replacement of motherboard for Acer aspire 7 i5 12450H series with rtx 3050 ?

I bought the Acer aspire 7 laptop which is i5 12450H generation about one and half years ago and now recently I reset my c drive and and after restarted the system works fine and no problem at all but after that I update the some windows update and then did restart and it can't restart other than it not started and not indicated anything so I went to retail store from where I bought the laptop and they said that it is not repairable and it need the new motherboard which is not available right now any where do I called the customer care and they said me that go to the authorised service centre it will surely change the motherboard with new one . So I want to know that what will be cost of that new motherboard? Please tell me and how many days it will take to repair that and is there any chances to lost the data of it then how I can recover that please tell me ASAP