I live in Brazil and I have a Wahoo Kickr Core trainer that I bought when I was living in the US.
The Wahoo service is not available in Brazil and it costs the same as a new unit to ship it to the US and back to Brazil.
Last year I had to service the bearings and it worked nicely. However, in December I got a lightning bolt close to my house and somehow the processor of the main board probably was damaged.
It was probably caused by some static electricity since the power source was not damaged.
I managed to do some tests and the speed sensor is sending the signal to one pin of the processor, so probably the cause is there in the processor.
My only solution, in addition to sending it back to Wahoo, seems to be finding a second-hand main board to replace. Unfortunately, Wahoo does not sell it separately. I begged them to BUY a new board, which would be cheaper than ship the whole trainer, and I would take the risk of replacing it by myself. However, they did not accept to do that.
Please, if you have a damaged Kickr Core, which the problem is not in the electronics, please send me a message.