I have a new laptop: HP 15s-eq2659ng. 
The installation of Manjaro Linux wrnt fine.
But I have a boot problem: the latest bios (F16) does not boot Grub, but only Windows 10.
In the boot order, there is only Windows Boot Manager.
I can choose Grub with some clicks with the Boot Manager of the Bios.
Silly question, are both Windows and Manjaro installed in UEFI? Or one of them is in BIOS, the other in UEFI?
Both are installed in the UEFI partition of Windows.
Is secure boot disabled?
Regarding EFI: I can enter the UEFI Bios boot menu with ESC + F9. There I can see Manjaro and Win10 boot entries.
Secure boot and keys are disabled.
Booting worked fine directly after installation Manjaro Linux.
Is os-prober enabled within grub config?
You could check and launch sudo update-grub afterwards.
I had a look at /etc/default/grub.
There is a line GRUB_DISABLE_OS_PROBER=false.
Then have started update-grub on console and Windows Boot Manager is found by grub.
What is happening then after reboot?
No Grub appears and Windows 10 starts only.
In BIOS setting you should be able to select which UEFI entry is launched by default.
There should be a Windows boot manager selected and a Manjaro grub listed below.
(Or just Manjaro, or just Grub…)
Exactly this is not displayed.
The single OS boot entry in the UEFI Bios, is the Windows Boot Manager.
Can I resort the boot order in the EFI Boot entry ?
In mine, I can add a manual entry. There, a not-displayed entry can be selected within the detected EFI partitions.
I can remember with efibootmgr -v you can display and resort the entries with Linux.
The UEFI Bios of the HP Laptop only displays one boot entry of operating systems.
When I use ```efibootmgr -v`` on console, then the windows boot manager is installed only.
How do I add the boot entry of Manjaro Linux (grub) ?
Here is the output of efibootmgr -v on console:
Timeout: 0 seconds
BootOrder: 0000,9999
Boot0000* Windows Boot Manager HD(1,GPT,842669e4-736f-4653-8b76-ad7d1964411d,0x800,0x32000)/File(\EFI\Microsoft\Boot\bootmgfw.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.}....................
Boot9999* USB Drive (UEFI) PciRoot(0x0)/Pci(0x1d,0x0)/USB(16,0)..BO
Reinstall Grub following the WIKI.
https://wiki.manjaro.org/index.php/GRUB/Restore_the_GRUB_Bootloader
From the system itself
sudo grub-install --target=x86_64-efi --efi-directory=/boot/efi --bootloader-id=manjaro --recheck
sudo grub-mkconfig -o /boot/grub/grub.cfg
Or from live USB, chroot, then execute the commands.
All how have answered to my question:
Thanks for the support!
The problem occured again.
Grub is uninstalled.
Maybe a second EFI partition solves the problem ?
How did it happen again two hours after it was fixed? What did you do?
I have started Windows 10 and then grub was removed.