No need to reflash. Just do as morseman says. You can also use the yellow composite phono (RCA) connector as well.
If you don't have a scart or composite cable, you can also try pressing the V.FORMAT button on the remote. Press it once, then again within a second or 2. Wait a few seconds. If the picture doesn't appear, try again until it does. I think there are around 12 different video modes, so using this method might take a bit of time.