Here are some causes and potential solutions if your Game Boy Advance SP (GBA SP) screen appears red.
Possible Causes:
Inspect the Battery: Display distortions (including color tints) can occur if the battery is low or failing.
LCD Damage — A defect or degradation in the screen itself.
Screen ribbon cable problem; A loose or faulty ribbon cable is responsible for causing color distortion by connecting the screen to the motherboard.
Backlight Type: If you own a front-lit (AGS-001) model, the lit screen can on occasion