I got a free g****r amp from someone at work. Looks like an older crate 15 or 20 watt combo. Anyways,you turn it on and at first the power light was blinking

So I fidgeted with the power supply in the back and then it stopped. Then i put my cable in the input and all i get is loud his,pop and hum. Like if you were to turn your amp up and unplug your cable from your bass and hold it against some metal. My guess is the input is bad,or is is it alot more?