recover Expansion after a non safe disconnect on a new NAS

[Race2018]

Can I recover the data on an expansion (TR-004) on a different NAS even if the safe disconnect I am supposed to do does not work? IIRC I connected the expansion once to the wrong NAS and I was asked for some kinda software key to unlock it.

(I have a pretty much broken TS-832x. The Raids /Hardware of the NAS are fine, as far as I can tell, but the Software / UI is almost useless. Many pages I cant open at all and if I can access something, it doesn't save the changes I make. One thing that (sort of) works is the filestation. Currently am copying files from the main unit to a connected expansion (TR-004). But I am not sure if I am able to do a safe disconnect when I am done. And as far as I know it is necessary to do so, to be able connect / recover the expansion unit on a different NAS.)

Please don't suggest contacting customer support or doing a 10s rest. I did contact them, they suggested the reset to fix the software / UI problem and it made things worse than before.