I have a new P1S and am trying to get it up and running. I get the error code on startup every time. I have adjusted the plug. I have exercised the cutter handle many times and it feels free, but I still get the error.
What am I doing wrong?
You could check the wiki and try Bambu’s suggested solution, and then let us know whether it worked or not. 
HMS_0700-4500-0002-0003: The filament cutter handle has not been released. The handle or blade may be jammed, or there could be an issue with the filament sensor connection.