This is a previous question rephrased:
How can one prepare for the restoration of an Android tablet after, say, a firmware update (in this case Lenovo, but the question is more general in nature) went awry? For Windows computers you can create a system image, to be used when there's trouble, but there doesn't seem to be anything like this for Android. What can you do up front to have a solution handy when an Android tablet remains frozen?
Preparing for Android system trouble?
Guest
There's a recovery menu which can be accessed if you power on the device holding certain buttons, e.g. Volume up/down. From here, you can factory reset your device, and depending on the control given by Lenovo, you may even be able to backup and restore the device ROM.
Frank