To find the key file Google: Use this to Encrypt your custom Amiibo NTag pastebinAlso, I don't understand how to create the key file for Tagmo. Any simple tutorial?
You'll find a .bin file, open in HxD and "split" it in two parts (the first 5 rows and the second 5 rows), then save the first part to "unfixed key.bin" and the second to "locked key.bin". Put the three .bin files (unfixed, key and amiibo) into your Android Phone, boot TagMo2, place a NFC tag under the phone and write the new amiibo