Oh dear, sorry to hear that. The USB can be tricky. I’ll get a video of me doing it released before your new Motherboard arrives. I think we can salvage the other one and just use the terminal blocks for power. If you find it, post a picture and we can get it sorted. A thinner tip and thinner solder will definitely help. I also find a magnifying glass with a light on helps tons too. Something like this: https://www.ebay.com/itm/373863355011?hash=item570bfe1283:g:Mt8AAOSwRaFh29Rb