Manjaro 20 XFCE Dual Boot with LMDE Debbie 4

I have installed Manjaro 20 XFCE alongside LMDE Debbie 4.I am getting a Bios Firmware error which asks me to press N to boot into another device,or boot into bios>.advanced>change to other boot devices.There is no problem booting into LMDE Debbie only occurs with Manjaro.I have triedto change Boot into other devices but cant find this in the Bios…Can anyone help me to resolve this? Thanks Michael

How did you install Manjaro? Are the two operating systems on one disk, or are each on a separate drive? UEFI or BIOS? HDD or SSD? What are the parameters of your machine?

this means perhaps you are using the grub from debbie.
as far as i have experienced, its better to let manjaro grub take over.
i happily triple boot my desktop with win10 / manjaro and MX all in bios mode and i have configured manjaro grub to take over ! [i installed mx grub in its own partition]

but as @zoli62 has asked, how was manjaro installed ? [with /boot/efi OR bios ]
same accounts for debbie.

another hint for multiboot. if one OS is on uefi, its advisable to install the other with same parameters [one uefi and other bios not advisable or safe method]