Why not re-flashing with the charger in ?
I usually do these steps in the following order:

1) power off the tablet
2) connect it via USB to the PC
3) run the flash command (I use linux command line). It waits for a tablet on the USB port
4) connect the charger to the tablet

At this point the flasher recognizes the tablet and will flash it.
When it has done flashing (i.e. the command quits back to shell)

5) disconnect the USB cable

The tablet will boot automatically (even if you don't do 5).