Hi Michael, welcome to the place!
I picked up a Fender Champion 600 a few years ago, and have had great fun tweaking and playing it. It is an excellent choice for trying your hand at this kind kind of modding.
I'm glad to hear that you replaced all the original components when you discovered the 'no sound' problem. Good diagnostic technique
A couple questions so that we're on the same page.
Before you did any modifications, it worked just fine - good sound, no excessive noise, static or rattle?
Besides swapping out tubes and speaker, did you do anything else to modify the amp before discovering the problem?
At this point, with the amp on, you can hear a hum, or slight buzz with the amp on, but no guitar signal?
The guitar and cord work in another amp (silly question, I know!)?
With the amp on and the volume all the way up to 12, can your hear any change in the sound the amp makes by turning the tone knob from one extreme to the other? If you plug a guitar cable into the input jack (try each one) is there any kind of crackle as the plug is inserted or removed?