Right Shayd,
You basically need to do exactly as I did, in order to get your unit fully updated and ready for the latest maps with 7 digit postcode search and loads of POI's.
1. Go to this website,
http://www.rnsfirmware.com/ and first download and install the 3810a firmware.
2. Then you need to download and install the 4020 firmware. (Both these firmwares' are modified, so that you don't need to recode your unit using a Vag Com cable.)
3. Now install the VUCI fix, from here;
http://dfiles.eu/files/a523wbwxf (If RNS-510 complains about downgrade error, insert media and reboot unit by pressing Setup + Eject + Info/Mic/whatever top right button together)
If you do it in this order you will not suffer battery drain issues and you will have the latest available firmware for your unit, which is a 'B' version, with video in motion and full 7 digit postcode entry.
PM me for any advice on the latest maps.