Owncloud Upgrade from 7.0.4 to 8.2.1 failed and broke my Owncloud server (RNXTRAS)

Hi,

yesterday I purchased the 8.2.1 bin from RNXtras to replace my owncloud 7.0.4 server. I also made an upgrade of my PHP from 5.4. to 5.6. Unfortunatly the owncloud upgrade page gave me an error and said that it is not possible to do a major upgrade from 7 to 8.2. So I reinstalled my 7.0.4 bin. But no I got stuck with a login loop not accepting my login and password. The log files also don't show errors.

What can I do now? I cant find update files for 8.0 and 8.1 on rnxtras.

Thanks

BR