a-four) Check out if the pins of the initial chip usually are not soldered very well (it was present in repair that the pins are tinned observing through the facet, nevertheless the pins are usually not stained with tin whatsoever once the chip is removed) Repair method: check the https://antminer-s19-pro-hashboar08641.bloguerosa.com/30682948/top-antminer-s19-pro-hashboard-secrets