Based on the information presented, I don't believe that Windows replaced or damaged GRUB; rather, I believe that Windows simply moved its own boot loader to the start of the boot list. The evidence is here, from the Boot Repair output:

efibootmgr -v

BootCurrent: 0000

Timeout: 1 seconds

BootOrder: 0005,0000,0003,0006,0002,0001

Boot0000* ubuntu    HD(2,96800,32000,1026f553-af9e-4aac-b975-418a07be36f0)File(EFIubuntushimx64.efi)

Boot0001* Hard Drive    BIOS(2,0,00)AMGOAMNO........o.S.T.5.0.0.D.M.0.0.2.-.1.B.D.1.4.2....................A...........................>..Gd-.;.A..MQ..L. . . . . . . . . . . . .2.S.G.A.J.N.C.M......AMBO

Boot0002  UEFI: Wbudowana EFI Shell     Vendor(5023b95c-db26-429b-a648-bd47664c8012,)AMBO

Boot0003* grub  HD(2,96800,32000,1026f553-af9e-4aac-b975-418a07be36f0)File(EFIgrubgrubx64.efi)

Boot0005* Windows Boot Manager  HD(2,96800,32000,1026f553-af9e-4aac-b975-418a07be36f0)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.}....................

Boot0006* ubuntu    HD(2,96800,32000,1026f553-af9e-4aac-b975-418a07be36f0)File(EFIUbuntugrubx64.efi)

Note in particular the BootOrder line, which specifies the order in which the EFI tries to run boot programs. The first entry in that line is 0005, which refers to Boot0005, which is the Windows boot loader.

This problem is easily fixed within Windows by using the bcdedit command from an Administrator Command Prompt window:

bcdedit /set {bootmgr} path EFIubuntushimx64.efi

bcdedit /set {bootmgr} description "Ubuntu"

These commands set Ubuntu's version of Shim, which in turn launches GRUB, as the default boot program, and sets a name that appears in some EFIs' boot loaders. (If you've disabled Secure Boot, you can change shimx64.efi to grubx64.efi, and in fact you may need to do this if Shim is not installed.) This solution is much less radical than running Boot Repair or re-installing GRUB in some other way, and is therefore less likely to cause unintended problems.

Some EFIs let you change the boot order within their user interfaces, and you can do the same thing with the efibootmgr utility within Linux. I describe the bcdedit solution merely because I know you can boot to Windows now.