I have a bought a new pc with a ryzen 7 1700 from MEDION. The PC works well under Windows and Linux with Secure Boot disabled. But the problem came when I wanted to enable grub with secure boot. As I did on my notebook I went to the secure boot settings on SETUP screen and added the grub to the allowed signatures of the secure boot. The problem is that after that the pc only booted the Antergos (an Arch Linux distro) and it couldn't boot any other thing, like a windows 10 cd.
This also happened me some weeks ago, that time I used the warranty of the site where I bought the computer. But now due to the very slow time to proccess the warranty I want to find a solution instead of using the warranty again. Is there anything I could do to restore this computer? Thanks