Power in the Radio???

so I had a Sony Xplod radio. CDX-CA650X
well a while back i lsot the harness so i just kept the radio in the garage. but i think i got alot of moisture in it... so i was looking on ebay to buy another harness but before i do so i wanted to know if it still works... How can i test the radio itself without a harness to see if it still works?

thnx for anyone who can help me.

you will need to be able to get into the plug and connect up switched power, constant power, ground and the speakers.