Computer doesn't detect Ubuntu after install

I spend hours and hours on google and I still have my issue.

I installed Ubuntu on a USB. I boot on the USB and install it on my computer (hard drive).

Windows was installed, but I did "Erase all and Install Ubuntu". I did the installation 5 times in the hope that it will fix the issue, but no.

I tried command to grub-install and grub-update and no.

When I open the computer without my USB, it found nothing to boot on. But if I boot on my USB, I can see on my hard drive that all the files are there.

What's wrong? Please help me!

If it can help:

ubuntu@ubuntu:~$ sudo fdisk -l
Disk /dev/loop0: 2.13 GiB, 2288189440 bytes, 4469120 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes

Disk /dev/loop1: 4 KiB, 4096 bytes, 8 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes

Disk /dev/loop2: 61.96 MiB, 64970752 bytes, 126896 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes

Disk /dev/loop3: 163.29 MiB, 171225088 bytes, 334424 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes

Disk /dev/loop4: 46.96 MiB, 49242112 bytes, 96176 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes

Disk /dev/loop5: 45.86 MiB, 48091136 bytes, 93928 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes

Disk /dev/loop6: 400.8 MiB, 420265984 bytes, 820832 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes

Disk /dev/loop7: 91.69 MiB, 96141312 bytes, 187776 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes

Disk /dev/sde: 232.97 GiB, 250148290560 bytes, 488570880 sectors
Disk model:  SanDisk 3.2Gen1
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0xa2f89d4a

Device     Boot Start       End   Sectors  Size Id Type
/dev/sde1  *       32 488570879 488570848  233G  c W95 FAT32 (LBA)

Disk /dev/sdf: 1.82 TiB, 2000398934016 bytes, 3907029168 sectors
Disk model: ST2000DM008-2FR1
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disklabel type: gpt
Disk identifier: 60781011-FC59-4CB4-BA82-DF2FEAC5CD03

Device       Start        End    Sectors  Size Type
/dev/sdf1     2048       4095       2048    1M BIOS boot
/dev/sdf2     4096    1054719    1050624  513M EFI System
/dev/sdf3  1054720 3907028991 3905974272  1.8T Linux LVM

Disk /dev/mapper/vgubuntu-root: 1.82 TiB, 1997809909760 bytes, 3901972480 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes

Disk /dev/mapper/vgubuntu-swap_1: 1.91 GiB, 2046820352 bytes, 3997696 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes

Disk /dev/loop8: 284 KiB, 290816 bytes, 568 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes

Your system has signs of both BIOS-mode and EFI-mode boot loaders. This makes for a confusing mish-mash, and it's not clear which way the computer had been booting in the past. Because you say you've wiped out Windows (although it looks like /dev/sde1 may be a Windows data partition), you have a lot of flexibility in how to proceed.

Before you do, though, you may want to read up a bit on the differences between BIOS and EFI (and UEFI, which is basically EFI 2.x). BIOS is the old firmware and way of booting, whereas EFI is the new firmware and way of booting. UEFI has been common on PCs for over a decade now, and EFI has been used for longer than that on Macs; however, if you're already familiar with BIOS-mode tools, you may be more comfortable with them. One trouble is that modern EFI-based computers support BIOS-mode booting through an emulator, known as the Compatibility Support Module (CSM), which creates complications. Basically, it can be hard to control the computer's boot mode when the CSM is enabled, which leads to confusion and frustration. I wrote a Web page that goes into this in detail.

The message from Boot Repair about disabling the CSM is related to this issue. I'm not one of the developers of this tool, but I suspect that they think it's easier to fix boot problems with the CSM disabled, at least when BIOS-mode booting is not required. Thus, you may want to start by doing that. You'll need to locate an option in your firmware setup utility to disable the CSM (aka BIOS-mode boot or legacy-mode boot). Unfortunately, there's basically no standardization on where to find such an option, so you may need to hunt for it or ask for advice on a forum dedicated to your computer. Once CSM is disabled, the boot process becomes more straightforward and predictable, as an EFI-only boot path.

If, with the CSM disabled, Boot Repair still can't get your system to boot, another option is to try my rEFInd boot manager. You can download the USB flash drive version, write it to a USB flash drive, and boot it. It should show you options to boot Ubuntu; however, the option to boot the Linux kernel directly probably won't work without modification because of your LVM configuration. You can highlight the option, then hit F2 or Insert twice. This will open a simple line editor in which you can add ro root=/dev/mapper/vgubuntu-root to the options. This should be enough to get the system booted. If this works, you can either try sudo grub-install or install rEFInd by typing sudo apt install refind. If you install rEFInd in this way, it should pick up the kernel options you entered manually, so you shouldn't need to do so in the future.