Christie LX50

I Have some DL2 units, no problems I cant deal with so far, but one of the christie LX50's has decided all it wants to output is a big white square of light. It wont display any image at all, from any input Composite, RCA Svideo or otherwise.Ive had it in bits, to check video input connections but they all seem fine. Im a bit stumped! Ant help out there?
Glenn Border
Luminaire Systems ltd NZ