This sound effect can be found on Series 6000 Extension I Sound Effects Library, which was made by Sound Ideas. It's the same sound as POWER DOWN - QUICK POWER DOWN OF MACHINE OR SMALL SPACE SHUTTLE, SCI FI from the Series 8000 Science Fiction Sound Effects Library. Links: https://soundeffects.fandom.com/wiki/Sound_Ideas,_ROBOTICS_-_ROBOT:_SHUT_DOWN#Audio_Samples