@BadGirlShaz: When you say your 'brightness keeps going down', do you mean your Screen Timeout time? Regarding the intermittent restarts, can you try heading to Settings > Battery and Device Care > Tap the 3 dots in the top right > Automation > Auto Restart At Set Times, and toggle this option off if it's active. Now, tap the Back button > Device Protection > Scan Phone to see if this flags any issues.
