The digitiser assembly not only has protective foil inside and outside the frame but also plastic protecting the adhesive strips. Sounds logical but I forgot to remove them making the first reassembly attempt unsuccessful. After discovering my mistake, everything went fine. Use a spudger to remove the protective strips from the glue
Another tip: do not glue the front panel immediately but test the iPad fucntionallity (Wifi antenna, front camera, LCD screen...) holding the digitiser panel in place with large paper clamps. Using clamps you can also keep everything neatly in place while using the hair dryer/heat gun to soften the adhesive to attach the frame to the iPad again