DTM0660L is used in many multimeters (ennoLogic eM860T, Tekpower TP40, UNI-T 139C, etc.). This video demonstrate adding UART communication/changing backlight duration by changing EEPROM data.
More details on my website: http://www.kerrywong.com/2016/03/19/hacking-dtm0660l-based-multimeters/
If you are interested in DTM0660L's datasheet please let me know. If there is enough interest, I can translate it.
