80°C is too hot for PETG. Try 70°C, and then try 60°C to see if that is better. It requires experimentation, and every machine will behave differently. Under most circumstances, you don’t want the bed to be hotter than the “Glass Transition Temperature” of the filament that you are using. Sometimes you MAY want it to be ~5°C higher than this for the first layer, but not most of the time. Once you get it to stick properly, I think you’ll get much better results.
As for an 11x11 leveling (Calibration), you need to do it over USB. Here is something that I posted a while back: