RN314 can't connect to admin page neither access bootmenu

Hello to the community,

I have several problems with my RN314 after updated to system version 6.6.1 and then to 6.7.0 Beta3 because of SMB problems.

1.  The admin page can't be reached. I get the same messages like https://community.netgear.com/t5/Using-your-ReadyNAS/Can-t-connect-to-admin-page-6-6-1/m-p/1221750#U1221750 or in other posts.
2.  I have tried to do a factory reset via the bootmenu, but the NAS boots only up to the point where I see the label Bootmenu. No selection can be done by the Backup button.
3. Fortunately I can access the device by ssh and so I have a backup of my data. But I see some errors in the log files of readynasd and mysql:
   
   

# systemctl status readynasd 
● readynasd.service - ReadyNAS System Daemon
Loaded: loaded (/lib/systemd/system/readynasd.service; enabled; vendor preset: enabled)
Active: deactivating (stop-sigterm) (Result: exit-code)
Process: 5325 ExecStart=/usr/sbin/readynasd -v 3 -t (code=exited, status=255)
Main PID: 5325 (code=exited, status=255)
Status: "Importing DB"
CGroup: /system.slice/readynasd.service
└─3669 /usr/sbin/readynasd -v 3 -t

Mar 11 12:00:59 Savemaster readynasd[5325]: DB (main) schema version: 23 ==> 23
Mar 11 12:01:09 Savemaster readynasd[5325]: rndb_create() ==> 3 (10366ms)
Mar 11 12:01:09 Savemaster readynasd[5325]: Error create table (db)
Mar 11 12:01:09 Savemaster readynasd[5325]: dba create failed
Mar 11 12:02:10 Savemaster readynasd[5325]: DB (main) schema version: 23 ==> 23
Mar 11 12:02:20 Savemaster readynasd[5325]: rndb_create() ==> 3 (10443ms)
Mar 11 12:02:20 Savemaster readynasd[5325]: Error create table (db)
Mar 11 12:02:20 Savemaster readynasd[5325]: dba create failed
Mar 11 12:02:20 Savemaster readynasd[5325]: Initialization failed. We don't want to keep retrying. Only twice.
Mar 11 12:02:23 Savemaster systemd[1]: readynasd.service: Main process exited, code=exited, status=255/n/a

#systemctl status mysql
● mysql.service - LSB: Start and stop the mysql database server daemon
Loaded: loaded (/etc/init.d/mysql; generated; vendor preset: enabled)
Active: failed (Result: exit-code) since Sat 2017-03-11 11:09:35 CET; 58min ago
Docs: man:systemd-sysv-generator(8)
Process: 2924 ExecStart=/etc/init.d/mysql start (code=exited, status=1/FAILURE)
CGroup: /system.slice/mysql.service
└─3048 /bin/sh /usr/bin/mysqld_safe

Mar 11 11:09:02 Savemaster systemd[1]: Starting LSB: Start and stop the mysql database server daemon...
Mar 11 11:09:35 Savemaster mysql[2924]: Starting MySQL database server: mysqld . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . failed!
Mar 11 11:09:35 Savemaster systemd[1]: mysql.service: Control process exited, code=exited status=1
Mar 11 11:09:35 Savemaster systemd[1]: Failed to start LSB: Start and stop the mysql database server daemon.
Mar 11 11:09:35 Savemaster systemd[1]: mysql.service: Unit entered failed state.
Mar 11 11:09:35 Savemaster systemd[1]: mysql.service: Failed with result 'exit-code'.

What can I do have access to the admin page and the bootmenu?

Regards

Rainer