Have you considered getting this into hfeasy?

[brujoand]

Theres this project to flash hf-lpx modules to better integrate them with HA etc over here --> https://github.com/ljalves/hfeasy

Seems like it would be a nice approach to get these heaters working properly without having to replace the MCU. Did you test it before replacing thi hf-lpt120?

[trondsundt]

I have not researched this no. I stopped researching once i realised i could power this with ESPHome. I will gladly accept code for the LPT120 if you create a pull to the repo