@aipei, how about leaving looking at green LED light aside, as I would like to know if you already separated Librem 5 battery from the phone for at least few minutes, turned all Hardware-Kill-Switches off and continued from fourth step, as described (and linked) here: Librem 5 not charging - #7 by mladen.
If red light constantly on, as it should be, perhaps leaving Librem 5 charging for some time (one hour or so, not sure how long) before pressing power button (turning phone on again).