The only problem with a cheap unreliable thermometer is that you are right back where you started and have no idea what is right.
I went through that for a couple seasons. In one incubator I had 7 different thermometers, most cheap and all wrong. I had one accurate one but didn't know it at the...
I'm not familiar with that incubator but it isn't unusual for readings to be off. You can use a different thermometer to verify readings and adjust from there. What makes me crazy is when the controls spaz out. Try cycling power a few times.
Sometimes computer controls just need a new start...