Maybe DJI stopped the emails since it understood a new complete P4 will be sent to you in exchange for the bad package. I had the same experience with an expensive tripod that came with a broken leg and after the email ping pong to exchange the tripod, all emails stopped like they never existed. New tripod came, sent back the bad one, never heard from them again.
There is another forum controlled by DJI with DJI reps as moderators, you could ask them for the complaint status, the new P4 may be shipped to you. Do not get PP involved unless you have checked all the options. Last resort is PP case dispute and can take a long time. If the other party makes a claim that they worked with you and an agreement was reached, PP will not refund the money.