This is a brick, unless you have a NAND backup then you may not be able to easily recover it. If you have a NAND backup then follow this guide and set up your SD Card with the NAND Backup and the GodMode9 app, boot into GodMode9 then install the NAND.
OK, first off, you'll need to familiarize yourself with how Android works, for one, drives may or may not automatically mount on Android due to the version of Android your tablet is running and if the manufacture added the feature, and it will also depend on what format the drive is in (NTFS, FAT32, EXFAT, etc.) If you are just trying to move files to/from your tablet from your computer, then you can simply connect your table to your computer using a USB cable. If it's a Windows computer then you shouldn't have to do anything but look for it in My Computer, but if its a Mac you need to download the Android File Transfer tool from Google.
Sounds like the pins for the connector may be damaged or not connecting properly with the battery, honestly the only fix is a teardown and double checking the pins. Although I suppose you can check with a multimeter while the power cable is plugged in and touch the appropriate pins to see if the pins are allowing current to flow, if not then you may need to re-solder the pins onto the board.
How many volts and amps is the charger your using? Also, if you can provide a photo of the data on the charger that your using and also the back of the tablet near the charger port where there may be some icons and text.
Turn off the tablet completely. Press and hold the Volume Up button. While holding the Volume Up button, Press and hold the Power button. Once the tablet turns on (you can tell because it vibrates) release the Power button but keep holding the Volume Up button. Once the Recovery Menu boots up, use the Volume buttons to navigate to Wipe Data/Factory Reset. Then press the Power button to select it, then confirm it and it should factory reset.
eBay has them for cheap, just search it, make sure when you take apart your Gamepad that you pay attention to the model number of your digitizer as you will need one with a similar model number, the first set of Gamepads have the pins layed out differently than the newer models, so if you mix digitizer models you end up with a upside-down touchscreen, basically when you move up on the screen, the screen will move down instead and vice-versa.