As Jack suspected, I indeed deal with information security for a living.
Furthermore I’d like to recommend to not muck with the device - at this point you’ve reached a point where legal advice is necessary I think.
As Jack said, if you’re on speaking terms, that’s the best solution. However, since you posted this question on the mailing list, I presume you’ve exhausted the on speaking terms options, so that’s why I made that stance.
Avoid mucking with the device and avoid attempting to restore. Also, avoid potentially dodgy things trying to sell you unlock methods. No publicly accessible unlock methods exist - some older devices are possible, but they require tens of thousands of pounds worth of lab equipment as weeks worth of effort and highly specialised skills - the cost of which is simply impossible to pay for as an individual. And even if you could, the few places which do won’t provide services for civilians and are catered primarily to the intelligence sector.
So yes - my initial advice still stands, which is to seek legal advice. The Citizens Advice Bureau is the best place to start I think. Legal support is available for free in a lot of cases, unless you are on a high income. The threshold for it to not be free is sufficiently high for most people to qualify for it IIRC.
Sorry for you having to go through this - I understand that it’s been stressful already up to this point, but there is little we can do here to help you I’m afraid.
/y