What should I do when the first layer of the print cannot stick to the Heated Bed or there is warping at the bottom of the print?
Follow the Quick Start Guide to level the heated bed again.
Make sure the heated bed is clean and no filament is left on the heated bed from the last print.
Use some alcohol to clean the surface of the heated bed. It can clear away some grease on the heated bed.
You can also select Raft as the Adhesion type when you generate the G-code.
Change the Initial Layer Line Width to 120%, 130%, 140% or 150% and see which value is most helpful for the print to stick to the heated bed. Please note that the bigger this value is, the more easily it will run out the nozzle. Therefore, if you don't have the adhesion problem, please use 100%.
If you are using the Custom mode to 3D print, you can also lower the Top/Button Speed and enter a bigger value for Heated Bed Temp Initial Layer and Printing Temp Initial Layer.
If the print still fails to stick to the heated bed, try using paint tape on the surface of the heated bed.
Change the sticker with the spare one.