I have just replaced a battery on my Galaxy Note 10.1. Today, after charging the battery to abt 65 % I attempted to restart the unit but it failed.

I have a figure code to open the programs but it would not accept my "drawing". I also note that the calendar on the front is january 1st (no Year) The clock is also incorrect. The unit automatically connect to my broadband router. What on earth can be wrong or have I done wrong?

Best regards

John Hegg