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..

The used processor will work fine...as long as it WORKS fine. You may be buying another defective processor. You may be buying one thats on its last leg.

The steps i would take are:

#1.
Connect to the processor and call lutron support and see if they can walk you through fixing the problem.

#2.
Assuming #1 didnt work ask if you can ship it in for repair.

#3.
Assuming #2 didnt work ask the client if they want to gamble with a used processor or replace the system.

I've got a job right now that's got an unstable HW8, and we're still working on what is the best course of action. In our situation, we have ~20 keypads and ~15 modules, all of which can be retained if we go QS, BUT we do NOT have the program. We tried to get it out, sent what we extracted to Lutron, and they said it couldn't be fixed. So we're pushing to upgrade to QS.

I think that even if we did have the program, we would still want to upgrade since it's not too big of a job and would be easy to replicate if it couldn't be converted (I've done Interactive to Illumination, but have yet to do Illumination to QS - only heard that it can be done, so that's another wild card).

If there were a bunch of modules that were out of date, the processor was dying and I didn't have the program, I'd push to flip it to Crestron. We're doing one of these next week, and awaiting approval on another one for later in the summer. These are LiteTouch jobs though, so it's an easier decision to make.

Don't feel bad about telling them they need to upgrade their stuff and that it may be expensive. As you probably know, that's relative in this field, and I have yet to see someone bat an eyelash as the cost of these things.

Have done a couple of Illumination to QS upgrades last year.
Both were large systems and went very well.
Lutron has a ton of info about what works and what doesn't, or will require extra bits / licenses etc.
Having the old program of course is ideal, but on a smaller project starting fresh should not be a big deal.
This is also an opportunity to let the client know about things they may not have had in the old system and might want to add to the new.
New model keypads and Occ sensors are a couple of popular things.
One of the upgrades I did went from old Seetouch KP's to Palladiom, and there were 50 of them (someone here will do the math).
If you did not do the old system, you may have a different programming approach that the client will like.
Finding an old Homeworks processor and saving the client money today is fine if they really do not have the budget to upgrade, and you still save the day by getting the system back up and running. But, they still have a system that is old and will eventually require you back to upgrade.