tina

Hi, we got a brand new Ultimaker2 and the first prints came out fine. But now I have a serious problem with burnt material on the nozzle. During the print something went wrong and the ABS material went all over the nozzle and got burnt. There is still a non-burnt bit of ABS filament at the tip of the nozzle (while the rest has a burnt coating) (see picture). Can anybody help me with this problem? Is there a method to celan it? (Step by step for dummies?). And how can I prevent problems like that? Thanks in advance, Tina