Sony s-master digital amplifier SPZ90DB micro hifi Fault Finding. Comes on for 2 sec then shuts off. Standby flashes but nothing works. Checked basic troubleshooting from manual but not resolved.

SOURCE: i have a sony 3 disc changer mini hifi stereo

I do not have any experience on your type of hifi but i reckon dest error refers to "Destination error" the 3 disc changer has a default home position of the disc carousel that it goes to when first starting up. I would suggest that somthing is preventing the cd mechanism from getting there to it's home when it starts up. This could be from a cd or foreign object jam, broken motor( or worn motor) broken or dirty sensor that detects where the mechanism is or broken cable connecting the two.
The key to finding this out after you fix the jam, would be to note if the mechansism is travelling, whether it sounds forced or if it's not moving at all. this will tell you whether it's motor or sensor related.
As I said I don't have any experience on this one, perhaps someone more qualified could comment...
Good Luck!