Hi Paul Donaghey,
Have you tried a hard reset on your tab?
''Be aware a hard reset will erase all your downloaded apps and user data. It will restore your tab to a factory default condition. It will be like when you first bought it.''
Back up your data, using the tab's backup feature before you hard reset your tab.
'''Note:''' If you restore the tab after performing a hard reset, with the backup you made, you ''may '' re-introduce the problem back into the tab e.g. if it was a downloaded app that was causing the problem.
Ensure the battery is charged before you perform a hard reset . Do not have the charger connected when you perform a hard reset.
Here is a link that show how to do it.
http://www.hardreset.info/devices/samsung/samsung-t530-galaxy-tab-4-101/
Be patient, it takes a few minutes.