Zend certified PHP/Magento developer

Can’t enter BIOS and grub is entering rescue mode

Ok so I have been dualbooting windows and linux mint for 1-2 years now and I decided that I wanted to try manjaro. I then did what I usually do when installing a new OS. I created a live USB and put manjaro kde on it. I then booted into the live USB and installed it via the GUI. I saw that the GUI had an option to ‘replace a partition’ so I decided to select mint and and insted install manjaro on that partition (still dualbooting with windows). When I then rebooted the pc I got a black screen and a commandline saying ‘grub’. I pressed ‘tab’ and saw that i could type ‘exit, which I did. Then I got into the bootloader and saw that ‘ubuntu’ still was the top priority then windows and manjaro was the last. I then decided try and fix this by going into the BIOS and simply change the bootorder. When I restarted the pc and pressed F2 I only got a black screen (not the type of black screen you get with your computer turned off, but a screen only displaying black pixels). My questions then are:
1. How do I fix the BIOS to change the bootorder
2. What did I do wrong?