Temperature

A bunch of printers are limited to about 250c. This is because the PTFE tube touches the hot nozzle. PTFE breaks down around 250c and one of the things it breaks down into is a carcinogenic gas. So the manufacturers have the firmware on their printers limit the temp to 250c.

In order to increase the temp beyond 250c you have to update the firmware with one that will let you set the temp above 250c. I can not help you with this. Now that the temp will go above 250c you have a choice. You can leave the PTFE touching the hot end and have it break down or you can replace the hot end with one, usually called all metal, that does not have the PTFE touch the hot bits.