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Just thinking aloud here…
Can you boot the install media when the laptop storage is installed?
If so, you can use gparted from the install media to clean the storage device and start from scratch. That might help.
You should be able to tell what mode to install the os in from the boot mode of the install media.
That is odd. However iirc it is an option in the bios.
Fwiw telling grub to uefi boot will not work if the boot device doesn’t have uefi support (and trying to boot in bios mode from a uefi disk fails as well… Been there got the T-shirt)
To get the install media to boot you could try removing the laptop storage…
On all the lenovos here hitting enter when the bios displays the Lenovo splash screen gives a menu that allows you to get at the bios or a boot menu.
You have to be a bit careful cos it’s on a countdown, paused and resumed by the enter key… And you have to get it timed right.
The translators did a heroic job. They even changed the names to make them funnier (Getafix is Panoramix in French). I do wonder what the Corsican’s name is in French given that boneywasawarroirwayayix is very English (language and culture) specific.
As a humble brag my Pa knew Anthea Bell’s brother - she was doing the English translations.