ReadyNAs Admin page not accesable on RN202

Hello, My RN202 worked fine until I got a harddisk crash with my laptop and I found out that recovering the files from the NAS was awsome. The firmware version is 6.7.1. and how I try I cannot access the admin page anymore. Raidiar concludes that all works fine, which in fact is the case as I can access all my shares, but are not able to manage them anymore. Using tools to login as root on the debian 8.8 linux of this machine I can find index.html in the frontview directory but I get the idea that files are missing as I cannot find other pages, which is in fact the same as I try to connect to the NAS with a browser, it asks my user and password and than it tries to find the correct pages, but cannot find them also. Is there a way to install this software from scratch on the debian linux kernel, this could solve the problem, as linux doesn't give any errort message and indicates that all siftware is up to date. I already tried to reinstalll the firmware on the hard way without any success.