Here is the trick to unlock your Sanei 76 tablet pattern and Gmail :
1) Download Android SDK and install Drivers
2) Open ADB in Command Promt (cmd)
eg : my adb file is stored in this directory
so to open adb inside this director i use the command
cd c:\android sdk\sdk\platform-tools\
3)type the command adb devices to check wether your device/tablet is connected to your PC
(if your device is connected you will get some thing like this :
4) Then type the command adb shell.
you will get some like shown below
5)if you got symbol rounded in the above screen shot download this file and run it.(if your device is not rooted)
6)The type su in adb shell
you will get super user privilages
7)Then type the command below
8)the type command reboot
9)Now you are done you are successfully removed your Gmail and Pattern lock.