"CRAZY noise" like Arnold Shoenberg singing karaoke?
Or do you mean hum?
If you mean hum or buzz, I would suspect the following source:
1. Is your cable a shielded instrument cable, or is it an unshielded "speaker" cable. An unshielded cable will provide crazy hum. This would provide hum with the piano turned off. Is the cable good? Does the sleeve at one end still electrically connect to the sleeve at the other end?
Other things to check:
2. Is one of the solder tabs of any of the 1/4" jacks involved (on the piano or on your amp) disconnected? Are the terminals that push against the jack still strong and springy so that they make clean electrical contact?
3. Is one of the legs from any of the potentiometers in the piano broken or disconnected?
4. Bees. Are there bees?
Sean