This is not standard method plugging into charging port using SD adapter. The S7 does have SD micro in the sim tray use that instead. I know these S7 as I repair them from time to time.
You need quality charging block that supports samsung devices and a good standard cable fully wired internally, not only Samsung devices, this is true of all devices even Apple's. Not the cheap stuff from the convenience stores and from the hole in the wall stores. Same with SD cards, has to be good quality too. Were you buying cheap ones and generic brands? My mother had a older Samsung and lost the data on SD card which was generic brand.
Plus anything this is not Google or Samsung, other than that, for example LG Huawei, HTC, devices does have hardware issues as they age especially battery and motherboard and impossible to get *new* parts for them. Same true for Blackberries. Sometimes Google has goofs too. For example, pixel has audio issues and battery, pixel 3 and 4 with their half life battery life (wouldn't go past 50% charging and replacing the battery fixes it and Google sends us batteries factory floor seconds (like labelled bent, green stickers, never top grade brand new), pixel 6 series with hard OLED meant broken screens very easily.
Yes we are authorized from respective brands. Fire sure brand new batteries is Apple and Samsung if you visit authorized repair shops.
Cheers,
Great Northern aka Canada.