Can’t sign out or in to iCloud on Macbook Pro

Yesterday I tidied my iCloud directory on MacbookPro but no changes appeared on my other devices. When I checked MBP, the sync was 84% done and it stayed there for hours, there were only few Mb of files moved. Not finding a solution, I tried logging out of iCloud on MBP. First it said password or id didn’t match. I checked iCloud.com and found I had to reset password. My other devices, iMac, phone, ipad are all fine with new password. On MBP I get various messages, none helpful. If I put the old password in it get the mismatch error. If I enter new password it goes tries for a while then different messages. The MBP still thinks it is signed in but I can’t sign out, can’t access account details, and can’t uncheck FindMyMac. Messages are “try again” , “can’t disable FindMyMac”. In desperation I removed the Macbook from within iCloud.com it has gone from devices but still shows in FindMyMac in iCloud.com. I was hoping it would see the MBP as a new device. The MBP is remembering the login and verifying password but just won’t do anything.