there's a bright white spot about the size of a quarter in the bottom corner of my 43s446 screen, it's always there.

Diagnosis

On the TCL 43S446, a bright white spot the size of a quarter is almost never a "stuck pixel" (which would be a tiny, single-color dot). Instead, this is a failure of the backlight diffusion system. The 43S446 uses an edge-lit LED array with a series of plastic diffuser sheets and a light guide plate (LGP) designed to spread light evenly across the LCD panel. When a bright spot appears, it usually indicates that the diffuser layers have become compressed, warped, or detached from the chassis. This is frequently caused by "pressure points"—either from over-tightening the VESA mounting screws on the rear of the chassis, accidentally pressing too hard on the screen during cleaning, or a manufacturing defect where a piece of internal debris is pressing against the backlight. Because the light is no longer being diffused, the raw intensity of the LED backlight is leaking through a specific point, creating a "hot spot" or "white bloom" that remains visible regardless of the image on the screen.

How to Fix It

Since this is typically a physical alignment issue rather than a software glitch, you can attempt to relieve the internal pressure causing the hotspot. Follow these steps precisely:

1. Check Mounting Tension: If the TV is wall-mounted, remove it from the bracket. Use a screwdriver to slightly loosen the four VESA mounting screws on the back of the TV. If the screws were driven in too tight, they can warp the thin plastic frame of the S-Class chassis, pushing the internal backlight components against the panel.
2. The Gentle Massage Technique: Power off the TV and unplug it from the wall. Use a clean, dry microfiber cloth. Locate the exact center of the white spot. Apply very light, circular pressure with your fingertip through the cloth, moving from the center of the spot outward toward the edge of the bezel. Do not press hard enough to distort the image; you are simply trying to "settle" the diffuser sheets back into their proper alignment.
3. Bezel Inspection: Inspect the bottom bezel where the spot is located. If the plastic frame is pinched or bent inward, use a plastic spudger or a credit card to gently pry the bezel slightly outward to ensure it isn't squeezing the panel.
4. Power Cycle: Plug the TV back in and turn it on to a solid grey background (available in the Picture Test menu) to see if the intensity of the spot has diminished.

If That Didn't Work

• Check for External Debris: In some cases, a small piece of plastic flashing from the internal mold of the 43S446 chassis can shift and press against the LGP. If you are comfortable with basic electronics, you can remove the rear cover and check for any loose screws or plastic shards near the bottom edge of the screen assembly.
• Panel Replacement: Because the diffuser and the LCD panel are bonded in a clean-room environment, you cannot realistically replace just the diffuser sheet. If the spot is caused by a permanent "dent" in the light guide plate, the only permanent fix is replacing the entire screen assembly (Panel Part No. varies by region, but check the sticker on the back of the LCD).
• Warranty Claim: If the TV is under its one-year manufacturer warranty, this is classified as a "Panel Defect." Contact TCL support with a photo of the spot on a grey screen; they generally replace the unit rather than repairing the backlight.
• Contrast Adjustment: As a temporary visual workaround, go to Settings > Picture > Brightness/Contrast and lower the "Backlight" setting. This reduces the intensity of the LED array, making the hot spot less distracting during dark scenes.

Heads Up

• Avoid Liquid Cleaners: Never spray glass cleaner directly onto the 43S446 screen. Liquid can seep into the bottom bezel, damaging the diffuser sheets and causing permanent "water spots" or streaks that look like white blooms.
• Mounting Caution: When using a VESA mount, ensure you are using the correct length screws. Screws that are too long can penetrate the internal chassis and puncture the backlight array.
• Pressure Warning: Never use a "pixel rubbing" tool or hard plastic objects to massage the screen, as the S-Class panels are thin and highly susceptible to permanent bruising or cracking.
• Heat Management: Ensure the TV has at least 2 inches of clearance from the wall to prevent heat buildup, which can warp the plastic diffuser layers over time.