This has happened on quite a number of phones thus far. Looking at ASUS's update lowering performance and seeing how the phone throttles on power use it seems the power IC simply cannot handle the new SD 888. I predicted this in my video already back then that phones would start dying much like the Rog2 after a year, but this seems to happen much faster than I anticipated. I don't know if ASUS has revised their logicboard design on newer models if not, we will soon have a ton of posts complaining about black screen issues.