eBay is a good first stop e.g. https://www.ebay.com/itm/SONY-Extra-Bass-MDR-XB650BT-OEM-Speakers-Cover-replacement-repair-part/113364539405?var=413617950633
I would mount the new fan in the original metal part. If you can't get the screws to line up you could use really good glue to hold it. The Dollar Tree has really good contact cement if you live near one. As long as the fan can spin freely and it's near the original location you should be fine.
When I charge my vivotab k0x for 8 to 16 hours the led stays solid orange. When I press the power button for a couple of seconds the led blinks 3 times, whether charging or not. Inserting a paperclip into the reset switch hole does nothing, holding the power button and the volume down button does nothing. What do 3 blinks indicate?