When I boot into endeavourOS I just get a black screen with a single _, this only happens when I disconnect my laptop to battery power. Once I am booted into endeavourOS everything works fine on battery power.
I hope someone can help me.
From within EnOS, can you post the output of the command sensors, after running sensors-detect as root, as described in the Arch Wiki on LM_Sensors:
https://wiki.archlinux.org/title/lm_sensors
Check your battery. Enter the following in the terminal:
a=`upower -e | grep bat` && upower -i $a
This will give you information about your battery. Please have a look at the status. Maybe it doesn’t have enough power to start in graphics mode.