Use precision tweezers to remove the two front or rear bands from the plate (depending on which band you broke), pull them out, push the new ones in (use hairspray if they are stubborn when inserted, as it will act as a lubricant when wet and the solvents will evaporate causing it to be dry and act as a mild glue. Some people also use spit), reconnect. As was stated, this risks scratching things. Alternative, you disassemble the whole thing, which involves the risk of stripping screws and damaging connectors with careless removal/improper tools.
As for the parts, you can buy the vibration board on eBay or on Amazon. It's $7 cheaper on eBay from an authorized DJI dealer.