Z4 SGP771 Stock Rom

Hi everyone. May I be advised on how to obtain SGP771 stock rom to flash my tablet back to default? There is a problem with my Z4 after installing Lucky Patcher and now, as soon as there is an internet connection available, my tablet will keep rebooting after showing me the home screen. It won't do so if I disable WiFi on the device. I will then get an error message that states "Unfortunately YouTube has stopped" I have tried disabling YouTube and uninstall lucky patcher but it doesn't work. It all started after I had chosen to patch unsigned apk. For your kind advice please on where I can get the stock rom.

Thank you