Presume the battery is good? The only way to sync them I've found is with Peugeot Planet (diagnostic software). Someone might be able to help you on here if they have the lead and software local to you.
Oh you'll also need the 4 digit key code to code it with Peugeot planet too.
Oh you'll also need the 4 digit key code to code it with Peugeot planet too.