se estropeo la instalacion al instalar el GRUB2

[Eduardo Gil]

estaba instalando ubuntu 18.04 en una version Beta

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: ubiquity 18.04.4 [modified: lib/partman/automatically_partition/question]
ProcVersionSignature: Ubuntu 4.15.0-13.14-generic 4.15.10
Uname: Linux 4.15.0-13-generic x86_64
ApportVersion: 2.20.9-0ubuntu2
Architecture: amd64
CasperVersion: 1.392
CurrentDesktop: ubuntu:GNOME
Date: Sat Apr 7 12:18:03 2018
InstallCmdLine: BOOT_IMAGE=/casper/vmlinuz.efi file=/cdrom/preseed/ubuntu.seed boot=casper only-ubiquity quiet splash ---
LiveMediaBuild: Ubuntu 18.04 LTS "Bionic Beaver" - Alpha amd64 (20180403)
ProcEnviron:
 LANGUAGE=es_ES.UTF-8
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=es_ES.UTF-8
 LC_NUMERIC=C.UTF-8
SourcePackage: grub-installer
UpgradeStatus: No upgrade log present (probably fresh install)

[Phillip Susi (psusi)]

Your disk is currently partitioned to boot in bios mode, but you booted the installer in EFI mode. A warning message prompted you that this could be a problem and recommended performing a bios mode install instead, but you chose not to. You either need to perform the bios mode install, or partition the disk using GPT and set up an EFI system partition to install in EFI mode. This will be done for you if you choose the "use entire disk" guided install option.