It would be difficult to get around the system's limitations. My colleague attempted to use the motor and gearbox with their own controller, but it did not work due to the complex network.
But I'm excited about your project if it pushes through. Best of luck!
You'll need a laptop, a vehicle-specific Vehicle Communication Interface (VCI), a backup battery, and a subscription to the carmaker's website. The VCI alone may cost more than the dealer charges for an ECM reflash.
To have Fiat cover the cost of replacing your battery, you must check and clear any error codes in the car's computer. Other people with bad batteries have been able to accomplish this.
Something might be wrong with the car's computer, causing the battery to drain. The battery charges whenever the key is turned on, even when the car isn't running.
Do you have any experience with electricals?
If the device is broken, you may be able to repair it by disassembling it and inspecting it for any issues.
Try looking here. I'm just not sure which is the right one...
https://www.alfashop.co.uk/products/4051023-500
https://www.autodoc.co.uk/car-parts/wheel-bearing-10679/fiat/500/500e-332
Does it charge and drive without any issues? If yes, then you can just try clearing the code using a diagnostic scanner. Don't fall too much on dealer's tactics.
It's got a decent power and range for its size actually, and based from what I read, most people prefer this over the Bolt. I haven't owned a Bolt myself, so I can't speak to the specific differences, but this one seems impressive.