You took out the SD Card, why? Also before you can control the aircraft you must tie the S/N# to you account with DJI. This activates the aircraft & records it as your responsibility, then the log into to the Pilot App with this same account (manually the first time then automatically there after...) & can take off.
Unfortunately doesn't work as such from my experience.
My Inspire was powered up, firmware updated and linked to his account by my friend before I took it for myself, and I had no problem using it with my own account afterwards.
It does however still show in his account in the Pilot app (and we didn't find a way to remove it), and no aircraft is showing up on mine.
Your problem is elsewhere then, either no communication between tablet and remote, or the remote isn't bound to the craft. First check you can actually browse the remote's settings, if you can't your tablet isn't talking to it. If you can then try rebinding the radio to the aircraft.