Small ZIP archive of 1.12 MB labelled with the TV model code LED28T3520, a 28-inch class LED television going by the name. The name gives no hint of the contents, so it may be a firmware dump, a service schematic or a mix of both. Technicians usually open such packages to get an SPI flash or EEPROM image for reprogramming a mainboard that will not boot, or to trace backlight and power circuits. Compare the main board and panel codes on the set with whatever the archive holds before flashing anything.
The button opens the matching file on RM Schematics, or a source page if it is not catalogued there yet. The original attachment is from @gunvantrathore. Enginerys does not host this file.
How to open a .zip file
Compressed archive that every operating system opens without extra software.