u/International-Poem41

I recently bought an inflatable vevor hot tub. From the beginning it has been very noisy when heating and now doesn't want to heat at all. The temp display goes up but the water isn't getting warm. After googling I have removed the filter. The noise has stopped and it seems like the heater is working! What can I do? The tub is new, I've had running for a month and only intermittently.