Im working on that myself, stuck at the same place. Im thinking of trying the following:
Hfvat syvc gb olcnff gur 5 oybpxf ba gur gbc yrsg, gura hfvat gur cyhf oybpx ng gur irel gbc gb npprff gbc yrsg fgne.
Rot13 as usual.
Okay that worked for the top left and top right, but now I'm stuck on the bottom right star. As far as I understand, the only way to reach it is to use the pluses in the central area with 7 boxes, but I for the life of me cannot see how that's possible. Unless I'm missing something, in either orientation, the blocks prevent usage of key to go up.