Hello @Thuanh,
If you got the new phone from Fido, then you start the return process through the method by which you got it. If you got it in store, then you have to go back to the store; if you got it online, then you can contact customer service, provided you are within the satisfaction guarantee period, which varies depending on the method you got it, see here for more details.
As for the e-SIM, it might be possible to transfer it to the old phone; if not, you will need to generate a new one before you return the new phone. See here for more details and instructions.
