Stand by /on led lights up but that is it. Click

Check the main power transformer.

ohm out the primary side should be about 2 ohms. and check for 120v ac when you power it on.

If 120v is present on the primary side check for ac on the secondary. if none you need to replace the tranformer.

If it doesn't have 120v ac on the primary there is an open fuse or bad solder connection.

If you find an open fuse check for a shorted output transistor pair.

good luck