Ive got a project where we have a HW4 processor that seems to have died. (It wont leave boot mode)

I followed this article (this is for HW8 but i adapted it) to de-solder and re-solder a new battery battery to the board but the processor still wont leave boot mode. [Link: forums.lutron.com]

Ive got a spec and price to update the system to a QS system but have also had someone offer me a working HW4 processor for about 10% of the price of the QS system + licenses i would need to apply to get the existing dimming modules, keypads etc to work.

Any considerations i should have in buying this used processor ? It seems like a no-brainer cost wise, but wondered if it the swap would actually work, or if t for what every reason would no integrate .. something like Lutron locking the processors so they can only be deployed to one system and not moved etc..