first of all, before you attempt anything with the drive like updating the dashboard or updating the hacked firmware, I recommend that you dump the key if you don't have a good copy of it or you are unsure of that. Follow the Jungleflasher tutorial to dump the key.
Once you have a good key, you will need to flash your drive back to stock, because first, you must update the dashboard to its latest version, and after that you can update the hacked firmware to the latest version. If you don't have the original/stock firmware in your benq at the time you take the dashboard update, the update will fail and it will lock your drive.
You should be able able to find the stock firmware for the benq in the latest firmware pack. Look in xbins. You just need to unpack it and browse the subfolders. Make sure to select the pre dash stock firmware folder for the benq. You will see that there are like 4 or 5 different stock firmwares for the Benq's. Pick any. It doesn't really matter. Eventually, this stock firmware that you pick will be your target firmware in JF.