Have just bought an 'old' kindle 4th generation which is new and unopened. I cannot register it/link to my account as the message keeps coming up that it doesn't recognise my amazon email/password.
What do I do? Have switched it on/off, have retried several times. always with same message. email address and password works for everything else.
The device appearing to be 'new and unopened' doesn't guarantee it can be used. If the device was originally purchased pre-registered to the buyer's Amazon account, it has to be de-registered from that account before it can be registered to yours. If the person you purchased it from is the original owner, they can check their Amazon account to verify it's registered to them (and de-register it). If the device was ever reported lost or stolen (or determined lost by Amazon's delivery tracking system), Amazon has blacklisted it and you'll not be able to register it.
You can check with Customer Service ('Help' link at the bottom of this forum or any Amazon page) for possible options but if the above scenarios apply, you're probably out of luck.