What is "causing" the "blockage" is the stabilization idler mounted on a plastic piece spanning the top of the recorder. It is a plastic disc with a metal ring embedded in it. It clamps down on the DVD once its loaded. It is supposed to release when the eject sequence starts. The read/write head assembly is supposed to rise up to read a dvd or cd and drop back down to a rest position when its time to eject the disc. The head assembly is encased in a metal shell, which is already magnetized or has become magnetized. The mechanism pulling the head down is too weak to pull the head all the way down. It moves just a little bit, you hear some noise and the "blocked" message appears on the display. If you take the cover off, you see the dvd still in the "mounted" position, but it has moved a little bit, but the clamp effect of the stabilizer is still engaged
Two ways to fix this:
First, before you go inside, tap the area of the phillips case right where you imagine the dvd center to be, if one was loaded. Tap and hit open, you may break the magnetic link that way, the head drops, the tray slides out. Then always keep a dvd in the player to give the release motor a little help, use a scratched disc you were going to throw away anyway. Second, you need to open the case, pry the stabilizer up as high as you can, or tap on the plastic near its edge while pressing the "open" button. You may need a PC type screw driver to remove the very small screws that the stabilizer assembly is mounted on. This way you can at least get the disc without further damage to it. You might as well leave the screws off, if you plan to keep using the recorder. Click on the link below to download the user manual:
http://download.p4c.philips.com/files/d/dvdr3455h_37/dvdr3455h_37_dfu_aen.pdf
