unusual transistor markings "C8550"
This is a really common cheap and generic PNP power/switching transistor in mainland China. It's inspired by the 2SC8550, but specs and pinouts vary (usually Japanese or US pinout, IME). 

Other similar part numbers are SS8550, SC8550 etc. 

It is often quoted with a silly high power dissipation intended for audio output type ratings. 

Example datasheet of a similar part here.