They make a thousand models. It sounds like the heating element has failed. Generic help and videos in the link but these machines need dealer service at regular intervals depending on the complexity of the particular model.
https://www.google.com/search?q=Dolce+Gusto+coffee+Machine+no+hot+water
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Question edited for clarity.
These machine need dealer servicing every 6 to 9 months depending on usage. They don't tell you this when you buy them, but I have been fighting these types of machines for the 9 years before I retired. One place had 2 machines and another has 6. Once machine did 1,200 cups a days and was serviced every month. Airport Business Class Lounges.
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To find Cecilware 3K-GB-LD Cappuccino machine error codes like "ERR 1," refer to the machine's user manual or technical documentation. Alternatively, contact Cecilware customer support for assistance in diagnosing and resolving the specific error code on your machine.