Here are the two parts to your request.
The chip model inside your tester (e.g., ATmega324, ATmega644)? lcr t7 firmware link
The most up-to-date code is usually found on GitHub. Look for repositories specifically mentioning the ATmega324PA (the microcontroller usually found in the T7). Here are the two parts to your request
Open the Case: Carefully pry open the plastic housing to expose the PCB. lcr t7 firmware link