Mine is broken POCO X3 PRO Suddenly it stopped working

it was like this: I was sitting on my phone, it was connected to charging and I was using it, and suddenly it turned off, turned on the white light, then the stripes, and I rebooted the reboot logo was displayed, then it stopped working altogether. Is it true or not, the repairman told me that I need to replace the motherboard and it costs about $40-45 is this a normal price.