Can not get cable to work using go app 4.2.20 on either Lenovo tablet or Samsung note4. Any suggestions ...

Is any device charging the other?
The RC has to charge the phone or tablet.
not the other way round.
Plig in firts to phone/tab and connect the RC plug just as latest .
After RC LED is steady red ( not connected to the Spark, which you start after RC and Phone is connected)

Hi, thanks for reaching DJI Forum. Have you tried to switch cables? Just to let you know the Lenovo tablet is not fully compatible. Try to switch cable to any compatible devices that are listed below. Please let me know if you still have further question. Thanks!

Try changing the direction of the Cable. Maybe its plugged the other way round.

Sorry for the trouble. As of the moment, OTG cable is still not officially recommended at present. Kindly follow the video tutorial below. if you have another concern, please let us know.