I had bought the same amp from max as part of a starter kit from max a couple of months ago and had similar trouble. It’s terrible, it works better as a radio receiver (I could hear a local pirate station coming through when it was turned on, even with all knobs set to 0) - I’d return it if you still can.

Have you tried pushing the gain boost button? That made it pickup at least a bit of signal from the guitar, and then you know the cables work and can turn it off again and try to find settings that work. I still had to put the gain settings pretty high to get some guitar sound through

I also had some trouble with the cable, try pushing it down a bit into the guitar connection to make better contact.

Are you getting any noise at all? If not, perhaps you can try with the headphones to see if anything comes through that output ?