Latest firmware for Topfield TF500PVRc is 3.56 from 2010 while for TF510PVRc and TF520PVRc there's 3.96 from 2013. Can you flash Topfield TF510PVRc / TF520PVRc firmware to older TF500PVRc? Yes, yes you can after changing SysID with VegaPack and it will start and appear to work just fine. However since TF500PVRc has only 32MB RAM system will quickly run out of memory. First menus will disappear and soon entire system crashes. Flashing newer model firmware "works" only for DVB-C models. In DVB-T models (TF500PVRt / TF510PVRt / TF520PVRt) tuner was changed and while OS will run it won't be able to receive any channels.