Thanks for the information.
I`m sure there are some facilities, but it`s probably only worth it, if your device costs several hundred dollars or is not available anymore. Google told me that simple repairs start from 120$ and more. A bit too much, unless I can be 100% sure that it works afterwards.
I`d love to send it to Mesa directly, but last time i wanted to order two cards, the shipping calculator presented me with a 250$ shipping fee. Todayy it`s 98$, but import taxes and tolls allways work in mysterious ways according to my experiences, so I refuse.
If nothing works, I can still use it as a huge I/O expander with a second ethernet port. I saw a video on youtube, where they connected two ethernet cards to the host with an ethernet switch. I think i read that one should avoid switches in favor of a direct connection, but my Raspberry only has one ethernet port. I will probably try it, if i order a new 7i76eu.
Anyway, thanks for the help.