It sounds like an all around software failure. Try to throw the tablet into '''safe mode'''
# '''Power off the device''', wait 3 seconds.
# '''Power on the device''' and wait for the "Samsung" boot logo to appear, often heard with a chime.
# Immediately press and hold the "'''Volume Down'''" button until the device continues to boot or at least 5-10 seconds.
# In the lower left corner, it should say "'''Safe Mode'''".
# Try to interact with the device as normal
Does the tablet still have bugs or failures with safe mode on? (Your tablet might be doomed for replacement..)