Hi, I have an SSD+HDD (on my HP pavilion 15 laptop) configuration on my laptop and recently I installed manjaro on the HDD. But after a certain BIOS update, I am unable to log into manjaro as the GRUB bootloader is gone. Upon startup, I see no options and it boots up directly into my windows device (SSD).
Can anyone help me out as I tried to restore GRUB by some of the methods mentioned on the wiki but no way seems to work.
I also have same problem first boot with live usb then reinstall grub. Topic is created
Here. Check it out for all instructions
If you only done a bios update so I guess that bios setting are restored. Have you try to set boot priority in bios to hdd instead ssd?
A bios update should not touch your disks. 
sometimes bios updates remove boot entry and as windows is in starting of disk it will be booted and it can create automatically boot entry and on other hand manjaro need it to be done manually
Bios update on laptop maximum time do remove entries and then try to boot from disk and first option of maximum laptops is Its preinstalled drive or sdd.
You need to disable secure boot as config of bios are removed when upgraded and need to be changed for linux
You should also give a try to rEFind just similar to grub but have its own boot entry and not get messed with grub update