Your tablet should not have run the battery down overnight unless the Screen Timeout was set on Never. To make sure the Screen Timeout is not set on Never do the following: (Home, Menu, Settings, Display, Screen Timeout - not set on Never). When the screen is off and the is tablet set to Standby, my A1 only uses a few percent of battery capacity per day.
Be sure to use the Lenovo transformer which supplies a higher current (1.5 Amps) then many phone chargers and a computer's USB port. The Lenovo transformer may also provide a higher initial charging voltage to improve charging a totally discharged battery. If the transformer is providing charge current it will be warm to the touch after 15 minutes. Leave it connected for at least 24 hours or until the tablet shows 100% charge. The green led comes on at 90% charge. Let us know if your A1 does or does not charge up. Good Luck.