You started this thread with the same problem the new owner is now experiencing. You said yourself in subsequent diagnosis that changing the data ribbon cable did nothing, then later on you are telling the new owner that it fixed the problem (“discovered that It was heat related and eventually I found the main Data ribbon cable to be faulty”). You also said that changing the audio board fixed the problem as well, though evidently you didn’t leave the replacement audio board in place when you sold it on.
I don’t have an axe to grind - I’m commenting on a new owner of this pin having the exact same problem you did when you were looking for help on here. The new owner may have made things worse by messing with the ribbons, potentially causing the new fuse issue, but he wouldn’t be doing that if he didn’t have a problem in the first place.
It seems obvious to me that the problem that started this thread was never really fixed - and if I was being uncharitable I’d suggest demoing it in preferable conditions where it’s cold or whatever is masking (or, less charitable, hiding) the problem rather than fixing it properly, particularly if it’s a heat issue as you yourself later suggested.
None of the above is any kind of commentary on anything else so going down the road of vendettas or other nonsense doesn’t help anyone.
@biglouieuk - double and triple check the ribbon cable that its not off, it’s very easy to get it wrong and it will be very hard to see without close inspection. Until that’s resolved there’s no point looking into the random sound issue.