I think the issue, about whether or not to break open the external casing, may now be moot. I cannot get it to recognise the drive today at all. I'll leave it a bit uplugged to cool down (in case heat is affecting it as the sound has changed so maybe the fans are not working as well) and then try again. If it still is not being recognised, I'll break the warranty seal and break the casing open to look inside and see if I can recover the remaining data some other way.
Listen to the whir of an unreadable drive
I think the issue, about whether or not to break open the external casing, may now be moot. I cannot get it to recognise the drive today at all. I'll leave it a bit uplugged to cool down (in case heat is affecting it as the sound has changed so maybe the fans are not working as well) and then try again. If it still is not being recognised, I'll break the warranty seal and break the casing open to look inside and see if I can recover the remaining data some other way.