HP ProBook doesn't boot into GRUB directly

Question

[SOLVED]: I had two fat32 partitions and my computer was confused which one to boot from

This computer is a ProBook 6470b, which is using UEFI (With CSM) mode.

When I start the computer, it will show a black screen saying "Operating System not found" more or less. This is like that since when I ran grub-install /dev/sda --efi-directory=/boot/efi && update-grub. I can run the operating systems I have but I have to press F9 to boot grub.

The thing is, every question about this problem mentions something about putting the grub efi file in /EFI/Microsoft/Boot/bootmgfw.efi or in /EFI/BOOT/bootx64.efi. None of them worked, which is weird since this error happened before but doing the "cheap trick" of putting grub there worked.

What would be a correct solution for this problem?

P.D: Sorry for any mistakes in the text, I am not a native English speaker.

P.D2: The computer's (main) operating system is Manjaro Linux.

P.D3: The EFI partition has the required boot flags (boot,esp)

Edit: output of ls -lR /boot: (I've ommited the OpenCore & grub things)

/boot:
total 90349
drwxr-xr-x 4 root root      512 ene  1  1970 efi
drwxr-xr-x 7 root root     4096 feb 26 14:27 grub
-rw-r--r-- 1 root root 28343586 feb 19 13:14 initramfs-5.10-x86_64-fallback.img
-rw-r--r-- 1 root root  7363769 feb 19 13:14 initramfs-5.10-x86_64.img
-rw-r--r-- 1 root root 29075497 dic 31 10:12 initramfs-5.9-x86_64-fallback.img
-rw-r--r-- 1 root root  7605230 dic 31 10:12 initramfs-5.9-x86_64.img
-rw-r--r-- 1 root root  3621888 nov 19 08:58 intel-ucode.img
-rw-r--r-- 1 root root       22 feb 10 11:42 linux510-x86_64.kver
-rw-r--r-- 1 root root       21 dic 21 22:59 linux59-x86_64.kver
drwxr-xr-x 2 root root     4096 nov 27 16:51 memtest86+
drwxr-xr-x 2 root root     4096 dic 14 08:11 syslinux
-rw-r--r-- 1 root root  8332704 feb 10 21:12 vmlinuz-5.10-x86_64
-rw-r--r-- 1 root root  8141120 dic 31 10:12 vmlinuz-5.9-x86_64

/boot/efi:
total 513
drwxr-xr-x 8 root root    512 feb 26 14:28 EFI
-rwxr-xr-x 1 root root 262144 feb 22 10:10 opencore-2021-02-22-091007.txt
-rwxr-xr-x 1 root root 262144 feb 22 19:13 opencore-2021-02-22-181308.txt

/boot/efi/EFI:
total 151
drwxr-xr-x 2 root root    512 feb 26 14:28 BOOT
-rwxr-xr-x 1 root root 151552 feb 26 14:25 bootx64.efi
drwxr-xr-x 6 root root    512 feb 21 17:59 EFI
drwxr-xr-x 2 root root    512 feb 21 17:00 endeavouros
drwxr-xr-x 2 root root    512 feb 21 18:27 manjaro
drwxr-xr-x 3 root root    512 feb 21 17:59 Microsoft
drwxr-xr-x 8 root root    512 feb 22 10:06 OC

/boot/efi/EFI/BOOT:
total 148
-rwxr-xr-x 1 root root 151552 feb 26 14:58 bootx64.efi

/boot/efi/EFI/EFI:
total 150
drwxr-xr-x 2 root root    512 feb 21 17:58 BOOT
-rwxr-xr-x 1 root root 151552 feb 21 17:02 bootx64.efi
drwxr-xr-x 2 root root    512 feb 21 17:00 endeavouros
drwxr-xr-x 2 root root    512 feb 21 17:01 manjaro
drwxr-xr-x 3 root root    512 feb 21 17:59 Microsoft

/boot/efi/EFI/EFI/BOOT:
total 148
-rwxr-xr-x 1 root root 151552 feb 21 17:02 bootx64.efi

/boot/efi/EFI/EFI/endeavouros:
total 0

/boot/efi/EFI/EFI/manjaro:
total 148
-rwxr-xr-x 1 root root 151552 feb 21 17:51 grubx64.efi

/boot/efi/EFI/EFI/Microsoft:
total 1
drwxr-xr-x 2 root root 512 feb 21 17:59 Boot

/boot/efi/EFI/EFI/Microsoft/Boot:
total 148
-rwxr-xr-x 1 root root 151552 feb 21 17:02 bootmgfw.efi

/boot/efi/EFI/endeavouros:
total 0

/boot/efi/EFI/manjaro:
total 148
-rwxr-xr-x 1 root root 151552 feb 26 14:50 grubx64.efi

/boot/efi/EFI/Microsoft:
total 1
drwxr-xr-x 2 root root 512 feb 26 14:28 Boot

/boot/efi/EFI/Microsoft/Boot:
total 148
-rwxr-xr-x 1 root root 151552 feb 26 14:51 bootmgfw.efi

Output of fdisk -l /dev/sda:

Disco /dev/sda: 931,51 GiB, 1000204886016 bytes, 1953525168 sectores
Modelo de disco: WDC WD10JPVT-60A
Unidades: sectores de 1 * 512 = 512 bytes
Tamaño de sector (lógico/físico): 512 bytes / 4096 bytes
Tamaño de E/S (mínimo/óptimo): 4096 bytes / 4096 bytes
Tipo de etiqueta de disco: gpt
Identificador del disco: 099E7E27-F334-4A5B-8DFB-F70D1B48507E

Disposit.    Comienzo      Final   Sectores Tamaño Tipo
/dev/sda1        2048 1748725759 1748723712 833,9G Sistema de ficheros de Linux
/dev/sda2  1748725760 1769207807   20482048   9,8G Datos básicos de Microsoft
/dev/sda3  1789687808 1810659327   20971520    10G Datos básicos de Microsoft
/dev/sda4  1810661376 1812758527    2097152     1G Sistema de ficheros de Linux
/dev/sda5  1812760576 1827440639   14680064     7G Sistema de ficheros de Linux
/dev/sda6  1827440640 1827850239     409600   200M Sistema EFI
/dev/sda7  1827850240 1953525127  125674888  59,9G APFS de Apple

Output of efibootmgr -v:

BootCurrent: 0000
Timeout: 0 seconds
BootOrder: 0000,0001,0002
Boot0000* Notebook Hard Drive   BBS(HD,,0x0).......................................................................
Boot0001* Notebook Upgrade Bay  BBS(CDROM,,0x0).......................................................................
Boot0002* SD Card   BBS(7,,0xa0).......................................................................
Boot0003* SD Card   BBS(7,,0xa0).......................................................................
Boot0004* manjaro   HD(6,GPT,19f0095b-c7a4-41ba-865d-556c8c75a3b7,0x6cec8800,0x64000)/File(\EFI\manjaro\grubx64.efi)

Answer 1

The problem was that I had two fat32 partitions and my computer was confused which one to boot.