Does the offer seriously and what should I pay attention to?
Can't really judge right now…
Jo you can trust nothing happens.
That may well be that nothing happens, e.g. That the part from China does not arrive or fails. Not to mention warranties in the event of a defect.
You should pay attention to this:
Although the article location is Frankfurt; the seller is sitting in China and also sent from there!
Always read the imprint!
What to do if the phone has / gets shortcomings?
Buyer bears the direct cost of returning the goods (Note: and those are horrendous to China)