@Homo_Erectus Try hitting enter. If the system does not respond, type "exit" them hit enter. You may be stuck on a grub shell screen that is not displaying, and typing exit will close it and should move along to either a full grub menu or the boot screen (depending on your PC set-up). One of my PCs does this to me so I can't reboot it remotely. It is an annoyance, but easy enough to work around once you know what to type at the grub shell prompt.