when i turn on the amp and start playing the guitar, everything is fine. then after a minute or so, sound goes off, only hearing a low humming bass. i turn the amp off and on again, and there is a load thumping noise repetitively which i cant control this sound, if i turn the amp off and wait for a few minutes, its back to normal, only after a minute it goes again etc.. any help? this amp is around 7 months old..

thanks

I would guess a bad solder joint. The connection has continuity when it's cold, but as it heats up, the pcb could expand and make the connection intermittent.
Just a guess, but I'd start looking there. Fender PCB amps have been known to do this.