I'm not familiar with that error message specifically but in but in general reflashing the firmware should fix it.
The latest W70 firmware can be found here: ftp://198.58.110.11/
I would give this one a go: ftp://198.58.110.11/W70-1.5.5-1680-NO-WIN8-1.10.zip
Instructions here: http://www.futeko.com/navpage/support-old.php#w70
I've not known it to happen with a W70, but for other Eken tablets this was the process for resetting the CMOS battery. It's worth a go:
Q: Outline of battery icon containing a red exclamation mark on boot?
A: This is a calibration problem between the battery and the Android installation. It is fixable by doing a hard reset. Connect the tablet to the charger. Hold the volume- button and the power button pressed in for more than 30 seconds. 45 seconds is fine. Remove the charger and leave the tablet for 2 minutes. Now plug the charger back in and press the power button. The tablet should boot normally. You won't lose anything stored on the tablet.