I'm new to Linux, but just loaded and installed Ubuntu 16.04.2 on my nephew's HP Pavilion Laptop (15-n037ncl).
Everything seems to be working fine except that the USB flash drive I used is now recognized as the primary drive, and I can't seem to figure out how to install and boot from the internal SSD. When I remove the USB drive and try to boot, it says there is no OS recognized.
Any help is greatly appreciated.
It is likely, as sudodus write in a comment, that your bootloader is on the USB drive.
This can often be fixed with boot-repair. The answer here will guide you how to use boot-repair to get the internal drive to boot properly.
You can read more about boot-repair here.
If you are happy with the current installed system and only want to make it independent of the USB drive, you can use Boot Repair as suggested in the answer by @John. There is also a direct link,
help.ubuntu.com/community/Boot-Repair
Ubuntu will be installed in the same mode as the computer was booted into, when you run the installer. So if the installer runs in BIOS mode, it will install Ubuntu for BIOS mode (alias CSM alias legacy mode). If the installer runs in UEFI mode, it will install Ubuntu for UEFI mode. It is possible to change mode, or even make the system bootable in both modes.
In BIOS mode, you can select 'Something else' at the installer's partitioning window, and at the bottom of the new window you can select the drive for the installer.
In UEFI mode, it looks like you can do it too, but the installer will select what it considers the first drive, /dev/sda, and install the bootloader on that drive, the ESP, EFI system partition. It ignores what you try to select.
You can convert between booting in BIOS and UEFI mode depending on the bootloader(s) that are installed. You can have either of them or both bootloaders (for BIOS mode and UEFI mode). See this link and links from it.
How do I convert my usb installation from legacy boot to uefi?
The conversion can be tricky (either way). If the installed system is new, I think it is easier to make a new and fresh installation in the preferred mode instead of converting it.
