Ordered a CRS326-24G-2S+RM in a third party shop, looked like original packaging, but had a strange label "SW#2" on the front and does not seem to work even after reset

Confusing. After ordering the named part from a german shop, I am suspecting that they sold a used (possibly bricked) part as new hardware. It came in what looked like original packaging.

It does not seem to boot correctly, as of now we are not even able to access the webinterface. Tried to reset the device two times, without any success.

What do you think? Or is there someone reading in the community who returned a faulty device with the label "SW#2" recently?

This is very likely going back, which is a pity due to the time wasted on return and resend of another unit.

Try netinstall:

I hope this "German shop" is not an official distributor, because in my opinion this is unacceptable. I am one of those people who always performs a Netinstall first, no matter what. However, many users will simply start using the device right away. It could contain a malicious configuration or other unwanted manipulation. Selling used equipment as new - even if it is only a returned item - is really inappropriate and unacceptable.

Got it working, it seems to have had a strange preconfiguration running. Netinstall would have worked, but we figured that a little tcpdump and arp-entry or quickly running a DHCP server, was sufficient to access the box.

It was now fully reset and updated.

Yea well, it is a bit shady. I dont want to disclose the shop here, but it is a normal popular shop for networking equipment. Official distributor, idk.

That's clearly a returned item with that SW#2 label - that's exactly where I put my labels on those switches...

Pretty dicey that they are selling that as new when it's clearly been used

Mail them this link to this thread, and to see how they will react.

You could also try reporting this to the German Consumer Protection as you seem to have paid for a new product, but clearly received a used one. If the product was not clearly marked as not new or "B Ware", then this is fraud.
https://www.verbraucherzentrale.de/beschwerde

wow, i hope they did not leave sensitive stuff in there too. worrisome for the previous owner too.