Note: Installing "free" firmware from unverified sources can permanently brick your device. Stick to the methods below.
A long-standing community for Chinese TV boxes. You can search their database for "S905L2" to find archived firmware links and flashing guides. amlogic s905l2 firmware free
Finding formal "academic papers" specifically on free firmware for the Amlogic S905L2 Note: Installing "free" firmware from unverified sources can
: Sites like GitHub host "clean" versions of firmwares for the S905L family, often compressed to meet file limits. amlogic s905l2 firmware free
: The standard Windows-based utility used to push .img files to the device via a USB cable.