In my experience this is caused by a damaged/loose ribbon cable that connects between the display panel (the actual glass) and it's associated circuit board. These circuit boards are typically under a metal shield at the edges of the display with other cables connecting the circuit board to the mainboard. It is the cable between the mainboard and the secondary circuit board that you likely reattached. Although unlikely, you may be able to locate the loose connection by squeezing/pushing on the edges of the display (with the rear cover removed, not the metal shields). If you find the location of the loose cable AND you can figure a way to clamp/shim the cable/connector it MIGHT fix the pink line. If you can't find and fix the loose connection you'll need to either live with the pink line, replace the entire display panel or get a new TV.