no way to install Ubuntu/grub...fatal error

[Brügger Bernard]

tried standard installation of Ubuntu via bootable USB: crashed "fatal error...grub..."
- W10 on Acer Aspire, laptop does not boot anymore

Disabled "secure boot" to:

- try fix via boot-repair, install via "something different" with new boot sdx

Ubuntu live-USB working ok
- no (!?!) boot priority entries in bios menu "boot"

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: ubiquity 20.04.15.10
ProcVersionSignature: Ubuntu 5.8.0-43.49~20.04.1-generic 5.8.18
Uname: Linux 5.8.0-43-generic x86_64
NonfreeKernelModules: zfs zunicode zavl icp zcommon znvpair
ApportVersion: 2.20.11-0ubuntu27.16
Architecture: amd64
CasperMD5CheckResult: pass
CasperVersion: 1.445.1
CurrentDesktop: ubuntu:GNOME
Date: Wed Jun 9 10:27:00 2021
InstallCmdLine: BOOT_IMAGE=/casper/vmlinuz file=/cdrom/preseed/ubuntu.seed maybe-ubiquity quiet splash ---
LiveMediaBuild: Ubuntu 20.04.2.0 LTS "Focal Fossa" - Release amd64 (20210209.1)
ProcEnviron:
 LANGUAGE=de_CH.UTF-8
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=de_CH.UTF-8
 LC_NUMERIC=C.UTF-8
SourcePackage: grub-installer
UpgradeStatus: No upgrade log present (probably fresh install)