The GT-I9100, also known as the Samsung Galaxy S II, is an Android smartphone that was first released in 2011. Firmware updates were periodically released for this device to improve its performance, security, and functionality.
Dirty flash or incompatible GApps. Fix: Boot back into TWRP, perform a Factory Reset (Wipe Data/Cache), and reflash only the ROM (no GApps first). If it boots, then go back and flash GApps. gti9100 firmware 511 download upd
First, the prerequisites: