[Filament]

Who's the company?

This company not very big. Medium company and only working i my country.

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notebook

What has the highest success rate depends on many factors so there will never be a "most successful" method.
First, I would check if the terms honor a refund from that long ago. Usually refund time period is only ~30 days unless you pay extra.
Getting a refund will be difficult. Wherever you purchased it from would have your order details so you cannot modify the proof of purchase to try to get within the refund time frame.
I'm thinking the best option would be to SE to get a replacement and then sell the replacement. If you think you'll be able to double-dip your replacement, then you can profit.

Okay thanks! I try leaking battery method.

Good luck
Let us know how it goes