Recently I have installed Ubuntu on a partition using Disk Management on Windows 10. Then I was able to login to Ubuntu but it would skip both BIOS and Grab screens. Before the installation I have disabled both Hibernate and Fast Boot and I would see BIOS screen.
Then I edited my Grub file by setting Windows 10 to default boot and now I cannot access Ubuntu. Since changing Grub file changed my default boot to Windows, I am guessing that the error comes from Ubuntu side.
And I've tried setting default boot loader to Grub:
bcdedit /set {bootmgr} path \EFI\ubuntu\grubx64.efi
But that also gave no effect. Also sometimes when booting, if I press SHIFT
the screen stays black until I manually shut down and power on again.