Hi @ Tom Tracey,
Here’s an image of the tablet showing the location of the “reset” switch, taken from the [https://data2.manualslib.com/pdf6/126/12565/1256449-polaroid/pdt9000_2.pdf?817c2f60097004bb6e02ecac430169b1|user manual].
[image|1980008]
Gently insert a straightened paper clip until you feel the switch operate, then hold it operated for about 10 seconds and then remove the paperclip.
''Be sure to insert it into the correct hole, as it is right next to the hole for the microphone and you don’t want to damage the microphone by inserting the paperclip into it instead''