Attempts to fix Grub failing

Question

My computer is only booting windows.

My most recent attempt to use boot-repair has this result. I have disabled secure boot in the bios.

I have attempted to set the boot flags using gparted as specified here. It's not clear to me whether sdb5, the linux partition, should have the boot flag enabled; I've tried boot-repair both ways. I have the boot flag turned on for the EFI partition, sdb1. I have two issues that come up on gparted:

It is unable to detect the file system on the windows partition, sdb2, as seen here:

And I'm getting the error "The driver descriptor says the physical block size is 2048 bytes, but Linux says it is 512 bytes." I think this is referring to the USB stick that I'm booting from; it's not clear to me whether this affects any attempts to use gparted on the hard drive.

Answer 1

The comments, especially from oldfred, have covered the fact that most of the "problems" you've identified in your question are not really problems. What we're left with, then, is what's in the first line of the question:

My computer is only booting windows.

This is a bit vague, but I suspect you mean it's booting straight to Windows. The reason is likely this, from your Boot Repair summary:

=================== efibootmgr -v
BootCurrent: 0001
Timeout: 0 seconds
BootOrder: 000C,0001,2001,2002,2003
Boot0001* Linux HD(1,MBR,0x61,0x3860,0x1300)/File(EFIBootgrubx64.efi)RC
Boot0007* ubuntu    HD(1,GPT,412f327c-c30a-4893-81c5-ad5ded944d84,0x800,0x32000)/File(EFIubuntushimx64.efi)
Boot000C* Windows Boot Manager  HD(1,GPT,412f327c-c30a-4893-81c5-ad5ded944d84,0x800,0x32000)/File(EFIMicrosoftBootbootmgfw.efi)WINDOWS.........x...B.C.D.O.B.J.E.C.T.=.{.9.d.e.a.8.6.2.c.-.5.c.d.d.-.4.e.7.0.-.a.c.c.1.-.f.3.2.b.3.4.4.d.4.7.9.5.}....................

(I've removed some irrelevant lines for clarity.) The BootOrder line specifies the order in which various boot loaders will be run. In your case, Boot000C, which is Windows Boot Manager, is run first. This is a common problem with two or three common causes. I recommend you read the following questions and their answers:

• Windows 8 removes Grub as default boot manager
• How can I repair grub? (How to get Ubuntu back after installing Windows?)
• efibootmanager -o changes are lost on reboot

These problems aren't identical to yours, but the solutions are pretty similar. In particular, using EasyUEFI or bcdedit in Windows is likely to fix the problem. Note that the last link is to a problem that's pretty dire, and increasingly uncommon. Go there only if other solutions don't work for you. (The fact that you've got an ubuntu entry in the efibootmgr output and a BootOrder line makes me think that it won't come to that for you, but I could be wrong about that.)