Kawai Synthesizers

I have just purchased a K1 ii and when switched on it looks all good until you play a sound. The sound is either a mixture of sounds that sustain or crackle and are a mixture of different sounds that either go up or down in pitch or are like a LFO has gone crazy but don't respond to the  keys pressed. I can change banks the noise stops but the same behaviour but maybe different sounds. Its as if the synth has a mind of its own. I don't know wether it may be the CPU or wave Rom or something else. The battery has just over 3 v and everything on the board looks good. Any suggestions or just throw it away?? The synth is in really good condition