Ttgjyuk

I've recently bought a new laptop, an Acer AN515-51 with a 250GB M.2 WD Black SSD drive and a 1TB WD Blue HDD drive, I' having multiple problems with Ubuntu 18.04 installation.

As always I've created an empty partition in the SSD drive in order to install Ubuntu there, downloaded the .iso file, used Rufus to create a bootable USB stick, restarted the laptop in order to get into installation.

The first time everything happened as it should be, but when I've got to the select partition to install Ubuntu the SSD drive wasn't recognized. I canceled the installation wizard and restarted the computer.

Got into Disk Manager, tried formatting and deleting the partition I've previously created on the SDD, restarted the laptop to go into the installation wizard but the laptop didn't booted from the USB stick, it went directly to Windows. I've restarted again, entered in boot menu and manually started from the USB stick.

Then I've received the message:

Failed to open EFIBOOTmmx64.efi - Not Found
Failed to load image EFIBOOTmmx64.efi: Not found
Failed to start MokManager: Not Found
Something has gone seriously wrong: import_mok_state() failed: not found

After that I've tried everything I know, tried to initialize the instalation by creating a USB stick with the GPT partition scheme and creating new USB sticks with other programs like Universal USB installer and Live USB Install, I've tried enabling Legacy Mode, tried to disable Secure Mode and for some reason I could not turn Secure Boot off in the UEFI mode on the BIOS menu.

Nothing worked, I always get the same message as above when I try to start from the USB stick. I don't know what else I can do to install Ubuntu on this machine. I hope someone can help me with this.

Also, whats the best dual drive partition scheme to use. One drive to each system, both Ubuntu and Windows 10 system partitions on the SSD and data partitions on the HDD (the scheme I'm already using with Win10). Any suggestions on this?

Thanks in advance