I'm trying to reinstall Ubuntu 19.10 from USB because of problems with GRUB

[SMS]

When I put Ubuntu 19.10 on my new Lenovo with Windows 8 already installed there came problem of loading Windows. It was second in the list and when I switched computer on or did restart, it always went straight to Ubuntu - there was no picture on display. I ran boot-repair putting Windows on the top and prolonging time to 15 seconds. I was able to load Windows but couldn't get into Ubuntu. On my old computer - with Windows Vista and Ubuntu 18.04 - there were no such problems. By the way, there were no problems during first installation alongside Windows.
This time when I tried to reinstall Ubuntu I had to cope with the message "No EFI system partition was found" followed with the warning about the problems with dual loading in case of continuing. The problem was that there was EFI partition on /dev/sda2 with fat32 named efi/boot : Windows Boot Manager. I deleted my three partitions (/, swap and /home), created and formatted them again and retried. The message "No EFI system partition was found" came again but this time I ignored it because there was a hint on internet that problems with EFI, GRUB etc. could be handled with bo:q! :aot-repair.

ProblemType: Bug
DistroRelease: Ubuntu 19.10
Package: ubiquity 19.10.21
ProcVersionSignature: Ubuntu 5.3.0-18.19-generic 5.3.1
Uname: Linux 5.3.0-18-generic x86_64
NonfreeKernelModules: zfs zunicode zavl icp zcommon znvpair
ApportVersion: 2.20.11-0ubuntu8
Architecture: amd64
CasperVersion: 1.427
CurrentDesktop: ubuntu:GNOME
Date: Sat Feb 29 05:48:00 2020
InstallCmdLine: BOOT_IMAGE=/casper/vmlinuz file=/cdrom/preseed/ubuntu.seed only-ubiquity quiet splash ---
LiveMediaBuild: Ubuntu 19.10 "Eoan Ermine" - Release amd64 (20191017)
ProcEnviron:
 LANGUAGE=de_DE.UTF-8
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=de_DE.UTF-8
 LC_NUMERIC=C.UTF-8
SourcePackage: ubiquity
UpgradeStatus: No upgrade log present (probably fresh install)

[Ubuntu Foundations Team Bug Bot (crichton)]

Thank you for taking the time to report this bug and helping to make Ubuntu better. Reviewing your log files attached to this bug report it seems that there is a problem with your installation media (CD/DVD). You can verify the integrity of the Ubuntu ISO files you downloaded by following the instructions at https://help.ubuntu.com/community/HowToMD5SUM. You might also retry your installation with new media. In the event that is is not in fact an error with your installation media please set the bug's status back to New. Thanks and good luck!

[This is an automated message. I apologize if it reached you inappropriately; please just reply to this message indicating so.]

[Launchpad Janitor (janitor)]

[Expired for ubiquity (Ubuntu) because there has been no activity for 60 days.]