after installing Mojave I had bad keyboard issues rendering the MBA unusable. The only option was to erase the ssd and downgrade to high Sierra. I made a bootable usb but it wasn’t recognised in recovery so I had to revert to lion the original operating system. Unfortunately, to do this I need to sign in to my Apple ID, and as the @ key isn’t working I can’t do it. This is turning into a nightmare, can anyone give me any suggestions please?