[spooky]

From what you have said i'd say that there is no trouble with the burning process as all the backups work fine on your friends machine.

So the only thing that is left is to double ##### the solder joints to the psx motherboard, sounds like the connections are in the correct place but there could be a possible dry joint.

Also ##### to see if the laser assembly and cable connections are seated properly.

Have you tried resetting the machine after its initial boot failier, this sometimes works.

Hope you get it sorted.