Chosen Solution

Replaced the flash hard drive on my iMac recently, everything works fine except no audios, check the audio device from “system report”, but nothing is listed there. I checked again connections between two speakers and logic board, it looks fine. So, what could be wrong? Any thoughts or suggestions? Thanks,

I suspect in the process you knocked the cable connection as outlined in Step 52 in this guide iMac Intel 27" EMC 2639 Logic Board Replacement Also make sure the cable and the contacts are not damaged. Update (06/26/2022) Here an image of whats inside your headphone jack