I forgot the name of the member here in the forum who offering to repair board. Much better to buy a new board instead than repairing the s7 board.
Anyway, maybe this thread could help you check this
https://bitcointalk.org/index.php?topic=1420909.0And this site bitmainwarranty.com just found it here
https://bitcointalk.org/index.php?topic=2728991.0But I don't think if they are actually safe always make sure that you read the whole thread first for some reply or reviews so that you are far from scammers.