It's a Fender Frontman 15G Amp, which is useful to me because it's small enough to fit on my desk, for when I give lessons. There's a pretty loud Hum from the Amp, mainly when cold & whether or not anything is Plugged In. This is with the Amp Volume set to zero.
The Hum usually Stops after the Amp has warmed up for about 5-10 min. For awhile the Hum was eliminated by [repeatedly] unplugging & replugging the guitar cable from the input jack of the amp.But now the problem is getting progressively worse & the Hum returns, even after the Amp has warmed up [& now there's even other noises: distortion?,crackling?,static?].

I'm asking your advice to confirm whether this Hum is likely to be caused by a cold solder joint of the Input Jack?... or something else?

To isolate the problem I eliminated: the Cables, A/B Box [Splitter], Guitar & Effects Pedal I normally use.

The problem appears to be in the Input Jack because I noticed I used to be able to eliminate the Hum by pulling the cable plug/tip part way out of the input jack,to the point where the plug/tip first touches the contact in the jack ; & then pushing up & down on the plug/tip [jiggling a bit]: I  would hear the hum stop completely & there was a click sound!  But this doesn't work any more.

I would appreciate any advice repairing Solid State Pyle-pro PVAMP30 30-watt Guitar Amp after a short circuit--The amp only hums & the pilot lite comes on.

I needed to demo a Denon AVR-4800 home theater amp [250 watts per channel] for a buyer,but I had no speaker available.
In a hurry, I connected the Denon amp speaker outputs to the Pyle guitar speaker input clips,
but did not disconnect the spade end plugs that lead from the Pyle guitar amp section to the guitar speaker input clips.
And I accidentally powered on the Pyle guitar amp.

Increasing the volume at the Denon amp I finally heard a screech & maybe a pop.
Now the Pyle guitar amp only hums,& there's no amplification--the pilot lite comes on [so the fuse is still good].

I opened up Pyle guitar amp section [I WAS careful to unplug the power cable first & not to touch the capacitors.]

I don't see or smell any damage & I don't see a 2nd fuse.

Haven't been able to find a schematic after  a bit of searching.

Should I send photos of the circuit board?