Greetings, fellow users.

Two years ago (or something close to that), I bough a Fender Mustang III amplifier and have used it without issues. For a few months now I noticed a dull buzz somewhere in the background to which I didn't pay much attention. Lately (for the past two weeks) the buzzing grew stronger and stronger and I couldn't have it checked due to time restraints. Today, while playing the guitar, my amp shut down, in the middle of it all. Waiting a few minutes I tried turning it on again, and it seemingly worked, but I'm really worried about it's current state.

Regarding the buzzing, as long as there's no cable plugged into the input jack(or slot, I'm behind in terminology) there's also no humming, only a sound similar to a soft breeze when I turn the volume up to ten. I'm saying this because the two button pedal the amp came with is still plugged in.

However, as soon as I plug the guitar in, the buzzing comes back. I've tried different cables, and using a new one the ammount of buzzing lessened but not by much. The buzzing noise is different at different levels. For example when having both the volume up to 2 or 3 (which is more than enough for my room) and the gain at 10, there's this constant fluctuation of a noise similar to that of static in the background of the buzzing.

While playing, the buzzing goes behind the actual guitar sound, however on a proper PA, I'm not sure how it would behave since I didn't really try it out yet.

I'd appreciate any input you could give me before I decide to take it to the shop hoping they can do anything to it. And should anyone need any further information regarding these symptoms, I'd be glad to offer them.

Stay safe.
If there's no buzzing with nothing plugged into the amp, that should tell you that there's nothing wrong with the amp.

Are you using the same guitar you've always used?
is it youre pick ups? are they active or no? could be a loose wire not hard to fix but thats probably unlikley unless its old or its been messed with b4
edit: plug yo guitar into anouther amp and see if that changes at all