SONY CDX CA680X problem - do i need a new ribbon cable?

I am thinking of buying a SONY CDX CA680X head unit, the only problem is that the seller says that when the flip face is pushed back the unit turns off. Could this be a faulty ribbon cable? I have heard of a similar fault on the Sony Xplode CDX M630 head unit that requires a new ribbon cable. Any ideas anyone? Is this a common fault? Thanks Chris.

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