A:AnswerHello Demi,
We regret to know that you are having issues with this unit, please check the link below and follow the steps provided to isolate the fix the issue:
https://www.sony.com/electronics/support/audio-systems-mhc-series/mhc-v21/articles/00025095
Regards,
Zac
Sony Social Support
A:AnswerHi there, Yes, the AC power cord needs to be connected. You may refer to pages 15-16 of this link:
https://www.sony.com/electronics/support/res/manuals/4736/81c840d6b8e3c09cbf28aaa8ae40784d/47366071M.pdf
~Ralph