David, please use Cura to upgrade the firmware as per my advice many months ago. You don’t need to use Xloader. Follow my instructions precisely. Marlin supports many 3D printers but the compiled firmware is based on a configuration file.
Someone went to the trouble of setting up the configuration file properly for the Creality Pro-20 and compiling Marlin. The hex file I used and you should use is the result of that effort.
I’ve been running my printer day and night for the last couple of weeks using PETG and will not go back to PLA. I’m running at the high end of temperatures for the bed and nozzle. Bed adhesion and “stringing” of filament are issues otherwise.
It depends on the model what build plate adhesion to use. I use “raft” for complex bases but set the “raft extra margin” to 3mm and “raft top layers” to 1.
I highly recommend OpenSCAD. Watch some video tutorials first and start with simple designs. It is amazing how easy it is to build complex parts with precise dimensions from cylinders and cubes.
