Buyer is asking for repair/refund on item purchased that he may potentially have damaged
Buyer purchased a used electronic from me that he has run into issues with. The item was listed as "AS-IS" (which I understand now means nothing) and it may require some general maintenance to use.
The buyer put a "very important" tape into the device upon receiving the device and now cannot retrieve the said tape. He is now asking for the seller to pay for device repair to retrieve the said tape and a potential refund/return. He has also indicated he will attempt to open the device to retrieve the tape.
My question is how to best handle the situation? I would have preferred the device to work correctly upon delivery as intended assuming that is the problem. The buyer has not provided many details (or pictures) on the issue and has mostly has relayed his plans/demands. Based on how valuable/important the stuck tape in question he has specified is, There is a pretty high chance that if the device is returned, it will come back more damaged than sent. Honestly, this may just be me, not sure why someone test a recent bought used item with something so valuable before testing with something less important.
Again just looking for suggestions on how to respond and proceed. I am new to selling on Ebay so I am not oblivious to the fact that I might have made some screw ups. Some insight would greatly be appreciated.