My MacBook Air (A1466) has stopped working. When I boot it up, it shows a flashing folder with a question mark. I figured the internal SSD must be damaged, so I bought a new one. After replacing it, the issue still remains.
So you replaced the internal SSD? If you’re not a professional technician, I recommend you visit a local Apple shop to see if the new SSD is properly connected.
Go to Recovery Mode and check if the new SSD shows up in Disk Utility. If it doesn’t, it’s not detected. If it is, you should erase the drive and reinstall macOS on it.