Don't know if anyone else had this issue. Let it be known that I upgraded all firmware, including BIOS. Prior to this, I have had Parrot Linux and Windows 10 Dual boot installed. I would be able to access them from Grub. However, after I updated the bios, my Grub loader disappeared off the boot options in BIOS and it didn't seem to matter what I did, I could never get it back... Until recently. I'm posting this so if anyone else has this issue, this may help them as it has helped me. What you will need, Linux live disk (usb), does not matter which distro. Windows 10 or other Windows OS of choice. Step 1: Linux Live Disk (Note: This step can be skipped if you know the folder your distro was installed under. I only listed the steps here in case whoever this helps doesn't know theirs.) 1. Boot into your Linux Live Disk. I'm sure there is several ways to do this, I changed the boot order in BIOS to do this. 2. Open terminal 3. type: sudo fdisk -l We are looking for the disk partition with the EFI System Type: In my case it was /dev/sda1. 4. Mount that device to /mnt. sudo mount /dev/sda1 /mnt. Make sure to use the device listed in the previous step for your EFI System. 5. ls /mnt/EFI Find the folder of your Linux distro. You will need this folder name when you return to Windows. Again in my case the folder was parrot. Step 2: Windows 1. Open a command prompt as administrator. 2. bcdedit /set {bootmgr} path \EFI\<distro>\grubx64.efi For <distro> change to the folder name retrieved from the 1st step. in my case the command was: bcdedit /set {bootmgr} path \EFI\parrot\grubx64.efi Step 3: If you have Secure Boot on, it needs to be turned off or you will get an error to get into Grub. 1. Make sure the device is powered off. Alternatively, you can tell Windows to reboot. 2. Press the escape key before the UDOO splash screen shows up and hold it to get into BIOS. 3. Press the right arrow key to move over to the Security Menu. 4. Go down to Secure Boot and press enter. 5. Disable it if it isn't already. 6. Save and reboot. If you have done it properly, Grub should now show back up and you can then load into either windows or linux. Pending you set Windows as a boot option in Grub. Hopefully, this will help others.
Kouruu thank you for sharing! I've posted this and the link to your topic in the BIOS update, hopefully it will help others. Thanks!