Hidari- Im sorry you have had a problem with your 360. But I can tell you that there are literally 10s of thousands of 360s out there and there is no universal problem with the power button. In fact, I haven't heard of a power button problem previously.
Things happen. It's one of the things you have to consider when shopping for something mail order from along distance, "What will I do if it breaks?"
Contact the service center directly
service@pocketbook-usa.com and ask them directly. If you actually want it fixed. Having purchased another reader already it seems like you don't.