I'm having trouble with my S4 - WIFI & Bluetooth won't turn on. Whenever I try to turn either on they just "hang" and won't switch on or off, so therefore won't connect. The icon turns light green then back to white, but doesn't actually switch fully on or off. I have switched off/on, taken the battery out (with & without SIM) & I've even rebooted and reset facto ry setting, but no joy ! Can anybody help, please ?:'(