Exclamation [Q] Nabi 2 Softbricked Help!!

Hi there I think I have softbricked my Nabi 2. I tried to update the software from ICS to JB using files from the XDA Nabi 2 Wiki but have come to a massive problem. I can't boot back into TWRP because all I get is an Android laying down with an ! on his chest. I can't re-install TWRP because my Windows 8 PC can no longer see the device!! I can get into the tablet options menu with fastboot, forced recover etc. I think the biggest problem is getting the PC to see the device.

If I try selecting different options in the tablet boot menu then Windows will see the device as Android ADB Device or MTP USB Device.

Can anyone help me get over this problem? I'm not used to using shell commands but fear I will have to install the Android environment to use ADB to get things working.

Please help if you can as this tablet belongs to a nephew of mine and he is missing his YouTube. I am close to tears trying to find the solution. I have read and re-read XDA posts in case I missed something.

Many Thanks In Advance.

Doozeman