any reason why not the s7?
it would be very hard for him to do to the s5/s7 that he did for s3 because the s5/s7 use a read only file system. so once you reboot it, it will get set back to stock

Is this why I can't change the root ssh password? Chinese need their backdoors.
It wont be a backdoor unless you leave your router wide open as well. Still, passwd doesnt work?
Password works but only default. If you change the ssh password (which is a pre-req in my book) it just reverts back to "admin"
Yes - I am a networking/security professional so I build my own firewall, virtual servers... all open source.