Citroen C4 1.6 Hdi BIS Unit

[oldmanbm]

Well my daughter's generally reliable C4 1.6 Hdi 'Loeb' has laid down and refuses to pretty much anything. Was sitting at a friends house for several weeks while she was away and now won't turn over etc Took a mate over yesterday who told me it's probably the BIS Unit has got damp. Is this a straightforward replacement or can the old unit be dried up and reset? Have this week to get sorted as car needed next! Any advice welcomed.