Yamaha P150 Initialization problems

by Gavan
(Lancefiled, VIC, Australia)

I have a P150 which refuses to get past the "initialize" "voice" state. factory reset does not seem to function and I get no "initialize ALL" when I try it. If I power on whilst holding down buttons 9, 10, 11 or 12 I get "initialize" "performance" but no further. No sound emanates from the speakers from either mode but connecting a sound source into line INPUTS, audio is heard so the sound module would appear to be working OK. Any pointers would be gratefully received, thanks.