I got the same problem. No controller, flash drive or anything via otg cable. Mine happened when I mistakenly insert the wrong AC plug that had wrong voltage and amps into Multi USB hub that was attached to the tablet and it fried everything that was plugged in , Tablet didn’t charge until minutes later it did but otg will not work. I think you might have to use a MutiUsb hub with Ac power to reset the bios or upgrade/install it (Might lead to you having to do full Android and windows installation).