I agree that's a huge issue.. unfortunately there is no S15 firmware that allows for ssh, we should at least have the choice to use ssh if needed.
I don't have any S15 yet, might want to contact Alex as it seems he's got ssh working on his S15?
https://www.youtube.com/watch?v=UJv6rrUNU60.
I contacted some guys some that say they could do it but in the end nothing!
Wanted money in bitcoin a huge quantity and the ones that asked little money and said could do it remotly never have done it, even with my agree to pay it.
Well, no wonder i couldnt do anything - my ftdi was broken. I got another and everything is working as intended.
So, can you post some video/pictures of all the process like diagram connections etc ?