verification failed unknown error occured

tried connecting to another wifi network, didnt fix the error. still cant sign out of my apple id, cant turn on icloud back up, error says icloud back up failed 'There was a problem enabling icloud back up.' on the icloud setting, it says "icloud storage datails are currently unavailablere. i did a hard reset too, apple id verification that says i have to enter the passwod for my appleid in settings keeps on popping up on my ipad screen and whenever i enter my password, i still get the verification failed error. can't do factory reset or any other options that would require my password because the ios system is not accepting my password only on this ipad. no issues with my other apple devices tho.connecting the ipad on itunes app didn't resolve the problem either

thanks for your reply

thank you so much!!!