I know it's a fairly common issue for the CPU to die on the 7 series and it's just not worth fixing.
You could reach out to a board repair specialist to see what they have to say. If you're out of the US, I believe iPad Rehab might be able to accept the repair. If you're in the US, both iPad Rehab and VCC Board Repairs could take a look at it. I've personally taken Rehab's board repair course and I send my data recovery jobs to Jesse at VCC. Good luck!