Trying to redeem a iTunes card on iPad keeps asking me to log in when already signed in. Any ideas
Meaning enter your username and password?
Are you signed in - Settings>Store>Sign In? Maybe try in the App Store in the bottom left corner - you can access your ID in the featured tab of the App Store - check there.
If you are signed in correctly - try signing out and then sign in again in order to refresh the account information.
Settings>Store>Apple ID. Tap your ID and sign out. Restart the iPad by holding down on the sleep button until the red slider appears and then slide to shut off. To power up hold the sleep button until the Apple logo appears and let go of the button.
Go back to Settings>Store>Sign in. Then try to redeem the card again.