At this time there is no way to extract 9.1.51 firmware so it can't be modified. I believe the ebooks are .txt files.
Have you followed the How to Remove a Memory hack yet? Many players on eBay are hacked. You can always contact the seller and see if you can reach a resolution or file a dispute with Paypal if the seller doesn't want to help you.
__________________
 ops: 1GB Black Hacked Chipod ops:
2 GB Black Temptation Player 
8) WHITE MEIZU M6 8GB 8) |