Hi @hjb2506 ,
Have you tried to ''reset'' the tablet?
This is from the [https://www.manualslib.com/manual/939708/Lenovo-Tab-2-A10-70.html?page=39&term=sd+card|User Manual]
''Please charge the battery for half an hour and then long-press the power key for over 10 seconds to restart. Press the Reset button behind the micro SD card slot cover, but please be noted that this method should be used carefully''