Not about Bafang its about Rize, do not give them any reason to deny a claim. OPs motor could have an issue down the road, he returns it to Rize and its been opened and is now full of after market grease? Why makes things complicated when they dont need to be?
Leave the motor alone and if there is an issue while under warranty get a shiny new motor with zero BS. After the warranty is over then yeah!
I dont understand why anyone would even consider opening and tampering with a new motor lol. These are the people that pop up later with some wild hate post yelling about how the company stopped responding to their emails and you should never buy their bikes lol.