As per the models chart:
Kindle Serial Numbers -- you have a PW1. firmware v5.2.0 is PW1 firmware, which is why it worked.
You should be able to apply any PW1 software update without need to flash partition images at this point.
PW2 updates will not work. You could force the matter by flashing partition images, but I can't think why you'd want to deliberately brick your Kindle.