I think it would be rather unfair to accept the sellers partial refund to only go back and say it's not good enough. If I sold something and it arrived damaged I would offer a part or full refund but once that was accepted I would consider the matter closed.
He offered a very small refund (about $40) which I, possibly prematurely, accepted.
It is playing on my mind a bit now and that's why I'm ascking on here.
Sending back to the US will be an absolute ballache.