Hi @candidrose ,
Some things to try which may resolve the problem:
Wipe the cache partition and then check if it works OK
If possible start the tablet in safe mode and check if it works OK.
If it does then a downloaded app is the cause of the problem. The trick is to find out which one. You will need to uninstall each downloaded app, one by one and then test the tablet in normal mode between each uninstall until it works OK. When it does then the last downloaded app that was uninstalled was the culprit. A downloaded app is one that you downloaded and installed on the tablet and was not pre-installed on the tablet when you first got it.
If still no good in safe mode then you can try a factory restore (aka hard reset) to see if this resolves the problem. Be aware that this will erase all your data and downloaded apps. It will restore the tablet to its factory default condition. Not a good idea unless you have a recent backup of the tablet either in the cloud or a computer, but it may come to this.
If still not OK after a hard reset then it is a hardware problem.