Apple watch activation lock

I had reset my iphone x when i gave it away to my sibling. When she tried to connect the watch (series 5), it showed activation lock was present so I put my old account details on it but it showed "This apple id couldnt be used to unlock this watch".

When I went and checked more about it I understood it was still connected to my old account and so i went to my icloud account removed apple watch from the devices.Even after doing all this it was still showing its activation locked.

I even tried putting out the old account again on my iphone but still it was showing the activation lock. So i then contacted with the apple support who now wants to see my proof of purchase for them to unlock my watch (its been more than 2 years so i dont think i could find it) . The apple advisor told me they would get back but still hasnt. Now after removing it from my icloud i cant no longer find it there too. What am i even doing wrong here? I went and removed it from my icloud just as they say but it is still showing the message to put my details which the app cant recognise. I dont even know what to do? Please help