Laptop not booting up after showing keyboard light

I bought my laptop in 2023 it was used for 3 years before I bought it, recently one day when I was preparing my presentations it closed and didn't opened again, keyboard light does shows up then closes aswell whole laptop closes, refusing to boot. I disassembled the laptop the fans werent spining when booting, only keyboard light showed up, I tried everything cleaned ram, took it out and tried to boot and fans spinned, keyboard light didnt turned off, it ran without issue but of course there was no display. Then I took the laptop to a local repair shop nearby they couldn't fix it and said gpu is faulty, like how? Can I still fix this myself or should I send it to Asus for repair which who knows how much it will cost especially if it is GPU then whole motherboard have to change unfortunately. Please help..