A friend of mine had the same issue with his x-t20. He contacted Fuji and he was informed that it's an internal battery issue. When saying internal battery, as I understand it it's like the battery that motherboards have in PCs.
In his case this battery needed replacement. Unfotunately we the users don't have access on that camera location, so if you have the same problem, you will need to send your camera to fuji.
Regards,
Vlad