Hi, I’m Louie. Sorry you had to wait awhile but I’ll do my best to help.
Initially , is the wireless keyboard completely/electrically dead?
Have you tried unplugging and then re-plugging back in the USB part? Do the wireless mouse work?
Still and if the batteries are new, then have you tried to clean the battery contacts using foam swab lightly dipped in household alcohol? ...and then allowed to air dry?
Please post back results / observations of the above once tried/checked.