If you tried all the steps listed (reincluding some below) then there is probably a problem with a button on the device, which is stuck. As long as that is stuck, it won't stay out of "Safe Mode" so you would need to get it repaired.
To get out of Safe Mode, please try the following.
1. Touch and Hold the "Power" key.
2. Tap "Power Off".
3. Once the tablet is off, Touch and Hold the "Power" key again to restart.
The tablet should now be out of "Safe Mode".
If the "Safe Mode" is still running after you restart your tablet, I would then check to make sure your "Volume Down" button is not stuck. Check to see if it has anything stuck in it as well, dust, etc. Anything like this can cause the tablet to go into, and get stuck in, "Safe...