You could try the NFS hack mentioned here to run a script which would change the password (or install an ssh public key to allow password less logins):
https://www.mobileread.com/forums/sho...&postcount=216
This is a bit complex to execute but it doesn't require working ssh access.
Edit: I've found an easier solution which doesn't require ssh access:
https://www.mobileread.com/forums/sho...40#post1915440