Hi @sisree ,
Try starting the tablet in safe mode and check if the lines are still there.
If they are not there when in safe mode then a downloaded app is the cause of the problem. The trick is to find out which one. You need to uninstall each downloaded app one by one and test the tablet in normal mode between each uninstall. When it tests OK the last downloaded app that was uninstalled is the culprit.
If they are still there when in safe mode, check if a factory restore resolves the problem.
Before you perform a factory restore, backup the tablet using the tablet’s backup feature.
Be aware that a factory restore will erase all your data and downloaded apps. It will restore the tablet to its’ factory default condition. That is why it is important to backup the tablet first.
Once the backup has been competed, factory restore the tablet using the tablet’s factory restore feature.
Once the tablet has been reset to its’ factory default condition, check if the problem is still there or not.
If the problem is still there then you have a hardware problem.
If it is now OK, restore the tablet from the backup that you made earlier, using the tablet’s restore feature.
Once it has been restored to what it was before you started, check that it is still OK. If it is then the reset has resolved the problem