Hi,
Ops circuit.
What is your 5V supply?
Feeding 5V into the Vin pin will not power the Nano or Mega properly.
With 5V going into Vin, you are powering an internal 5V linear regulator, and it will not function properly with 5V input.
You need to connect your 5V supply to the Nano and Mega 5V pin.
Are you using a 2020 or a 2022?
Tom... 
Avago HCTL-2020datasheet.pdf (167 KB)