This may not be very helpful but I had a similar problem with a Daewoo DVD recorder and as far as I could find out, there is nothing you can do. It may be possible to finalise if you can borrow etc another identical machine - not just same make, exact same model as they all have different formats - but Daewoo would not guarantee me this so I didn't go to any expense trying it out as I was not very happy with them by that time.
Brighter points: DVD+RW discs do not seem to need finalising (although all others do)
also, looking on forums lead to suggestions of using a piece of software called isobuster (do a google search) which can apparently read different formats although again I haven't tried it. I think it needs to be downloaded to a PC then you rip the content off your dvd and save it in a different format. Don't know whether you can use it again in a dvd player or just on a PC - as I say, I haven't got round to trying it.
Anyway, good luck!
Annie B
February 2008