The “Mega” update isn’t an official marketing name like "iOS 18." In the security hardware world, "Mega" usually refers to support or a Mega-Feature bump. Based on patch notes from iStar’s legacy servers (and user reports), the A7500 Mega update (likely version 4.5.x or similar) focuses on three things:
Format a USB drive to FAT32 and copy the firmware file (usually ending in .bin ) to the root directory. istar a7500 mega software update