change study visa to work type

Fritz, you should first go to the exit and entry administration of the local PSB and consult if you can change X type to work Z type from there. If yes, you need to prepare the required documents containing the completed application form attached with a passport-style photo taken recently, your passport and copy of its data page, as well as the foreign employment permit and the invitation letter of duly authorized unit (the employer will get the two documents for you). And then you can change X type to Z type.
But if you cannot change it from there, I’m afraid you need to go back to your home country to apply for a work Z type.