Scottsville

HI, New to the for forum. I bought a xt2 with older update. I updated it to the newest firmware and the lcd screen started going bright them dim then bright then dim constantly. Tried to video and says problem with card. I have a xt4 and the card works fine in. It worked fine in it before the update. Has anyone every had this problem or know how to get it fixed? 1st camera problem and have no idea! Thanks in advance. Scott