Dear KKYOUNG,
It seems reach the time to repair stage :(
My friend did have a Samsung DVD+VCR but not sure is it same model as yours. It cannot turn on by pressing the power key any more.
No, my friend did not take it to repair. He gave it up and bought a new BBK one.
For repairing, I suggest send back to original service center since these high intergrated (not high tech) products may not be repaired by 3rd party easily, or not reliable.