Actualizar arranques en grub2:

sudo update-grub2

Instalar super-boot-manager: Para Loki

sudo add-apt-repository ppa:ingalex/super-boot-manager

Para Juno

sudo add-apt-repository ppa:danielrichter2007/grub-customizer
sudo apt-get update
sudo apt-get install buc 
sudo apt-get install super-boot-manager
sudo apt-get install grub-customizer
sudo apt install plymouth-themes

Instalar Burg:

sudo add-apt-repository ppa:n-muench/burg
sudo apt-get update
sudo apt-get install burg burg-themes
sudo burg-install /dev/sda (¡OjO al disco que debe contener el MBR!)
sudo burg-install /dev/nvme0n1 (en el XPS 13 9350)
sudo update-burg

Probar los temas:

sudo burg-emu -D

Opciones

• t – Open theme selection menu
• f – Toggle between folding mode
• n – Jump to the next item with the same class
• w – Jump to the next Windows item
• u – Jump to the next Ubuntu item
• e – Edit the command of current boot item
• c – Open a terminal window
• 2 – Open two terminal windows
• h – Display help dialog (only available in sora theme)
• i – Display about dialog (only available in sora theme)
• q – Return to old grub menu
• F5/ctrl-x – Finish edit
• F6 – Switch window in dual terminal mode
• F7 – List the folded boot items
• F8 – Toggle between graphic and text mode
• F9 – shutdown
• F10 – reboot
• ESC – quit from the current popup menu or dialog.

Tema Metro

Arreglar arranque con boot repair (factible desde una live):

sudo add-apt-repository ppa:yannubuntu/boot-repair
sudo apt-get update
sudo apt-get install boot-repair

Boot-Repair - Para los problemas con el arranque (Windows, Linux):

sudo add-apt-repository ppa:yannubuntu/boot-repair && sudo apt-get update
sudo apt-get install -y boot-repair && (boot-repair &)

Instrucciones de uso en https://help.ubuntu.com/community/Boot-Repair

Eliminar núcleos antiguos - Liberar espacio en /boot:

dpkg --get-selections | grep linux-image  -> lista los núcleos instalados
sudo apt-get remove --purge linux-image-3.2.0-51-generic  ->  borra el núcleo indicado