Question about Creality Nebula Smart Kit

I have ordered the Nebula kit for my Creality Ender 3 Pro. When I tried several times to install and set it up according to the instructions (firmware etc), I always get the "Warning , key:2022, Unknown exception", apart from a brief whirring noise, nothing happens. After I have reinstalled the old control unit, the printer works perfectly again. Again, conversion to the Nebula kit = same problem. I am grateful for any support!