Here is how I flashed a firmware without access to recovery:
If you are in a bootloop, Connect USB and Power.
Press and hold pin on back until you hear windows try to detect a device but the screen is off.
Download this: http://arctablet.com/assets/tools/Fi..._Tool_v1.4.zip
Install the driver from the drivers folder.
3. Installing the drivers on the computer
Following the tablet entering in recovery mode, the computer should now show it has found a new USB device and prompt for a device driver. Select the appropriate driver in the driver directory from the Rockchip Flash Tool 1.4 package.
It will then install the driver for RK29 Device
4. Sending the firmware to the tablet
The flashing tool should display a green square around the number 1 in the lower left area of the Windows application.
Select the firmware file to flash using the button in the top right area of the application. Select the update.img file from here:
Then push the Upgrade button to transfer the selected firmware to the tablet.
The firmware will be copied to the tablet, a progression counter will go from 0% to 100% on this step, followed by a verification.
You are done, let the tablet reboot and update itself. It should take a few minutes for the flash process to finish.
This procedure has been successfully tested on Windows XP 32 bits for flashing a bricked NextBook 7 Premium YF1011 (but should work on others)