Wont charge. new roomba for xmas. lights on charging unit both flashing but no power in

Question

new roomba for xmas. lights on charging unit both flashing but no power in roomba.
it worked yesterday when i got it out of the box and did a full clean. i feft it on charge over night ready for the clean today but when i got up no power atall
please can you offer a solution. i have held down pock and start - no joy. i have checked the battery connections - no joy
please help
many thanks caroline