My Marshall AMP not working. Please help :-)

Hello,

I own a Marshall JVM 215c. I purchased this when I was living in Portsmouth. I didn't have much of a chance to use it as I was also studying for a degree at the time. I then moved up North. So 7 years later I'm in a position to crack back on with guitar (finally).

So I dust off my JVM 215c. Turn it on. Nothing happens. There is sorta a thump sound when I turn the power on. But then nothing.

Does this sound like a valve issue? And if so, is it easy to fix myself? Or does this amp need a professional to look at it?

Kind Regards,

Lee