Edit: I just saw there’s a preliminary new modem.zip, but I didn’t use that yet …
So … you can flash the new modem files, and you will get the fancy fastboot mode LED and vibration, and you can turn on the phone again while charging, but if you want the modem files for fixing e.g. the shutdown bug, those fixes are somewhere else, as explained here …
https://forum.fairphone.com/t/fp2-fairphone-os-fairphone-open-19-02-1/48239/30?u=anotherelk
And in case you want to try flashing the Fairphone (Open) OS boot.img to a LineageOS installation …