A specialized port for the T7H hardware (which uses the ATmega644 MCU) can be found on this GitLab page k-firmware (Karl-Heinz Kübbeler's version):

This is the "home base" for the original project. The forum threads here contain the most technical discussions and direct download links for compiled .hex and .eep files.

Here’s a of what you’ll find when searching for an “LCR-T7 firmware link” — based on common user experiences with this popular Chinese component tester.