I pulled out the D703 after a year of non-use. It worked fine before. But after turning it on and pressing Open, the LCD will display 'CLOSE', the gears/opening mechanism makes grinding sounds for about 5 seconds (the typical 'tray opening sound', except it doesn't open), the LCD then quickly flashes 'OPEN', then everything goes silent, the display showing 0h 00m.
I tried a few tricks like pressing disc side change, chapter skip, hi-lite intro, etc. I can't get the tray to
open. I'm worried about trying to force it open.

Sorry to post another link but it also sounds very similar to a problem I had.

My problem was that the part that changed the gear mechanism from open/close to read was broken, as a result the gear was always in the open/close position and was always trying to retract the tray and never went on to read the disc.

The only way to be sure what's causing your problem is to open up the player and have a look. It was something I'd never done before but I still managed to get my broken player into a 100% working order so it's not really as daunting a task as it may seem.

Good luck!

The unit is out of sync for the mechanism moving up and down verses opening the tray. Both are happening at the same time. Thus the grinding sound. I can help you thru it or you can send it to me for repair.