Tab A 10.1 Unknown pattern required after update

System update was recently completed. After the update, the tablet now requires a pattern to sign in but one has never been used on this device. It also requires a pattern to turn off or reset so a hard reset can't be performed. I managed a soft rest (power + vol down) but that's only made things worse as now it's not logged in to a google or samsung account so remote erasures can't be done either. It's also won't bring up any sort of 'forgot my pattern' dialog, it just keeps showing a 30 second timer after every 'wrong' attempt. Is this a known issue? How to I get around it? I'd prefer to save my data, but a complete factory reset is still an acceptable solution.