Bionx I2C Rescue!

First post here - hi everyone!
I recently bought an older hybrid bike (pre 2009?) with a Bionx conversion that I'm trying to get going. It's the 36v version with the I2C bus. The seller thought the battery was dead but I've managed to coax it back to life and it's currently taking a full charge but, given it's age, I doubt it'll last long.
In testing it I briefly had the screen lit up and the motor spinning the back wheel so I believe the motor is OK. Unfortunately, while testing I managed to blow a chip on the PCB so it no longer turns on but will still accept the charger. (I have photos I can add when I figure out how to downsize them)

So, here are my questions:
Short term.
1. Can I get the motor and computer to work inexpensively to enable using the existing battery, while it lasts?

Longer term.
2. Can I retire the current battery and replace it with a couple of 18v cordless tool batteries, like Ryobi or DeWalt? I understand the Bionx is proprietary and not readily accepting of 3rd party parts. But I'm not able to do a lot of fancy electronics stuff myself so is this going to be a show stopper for me?

3. Failing that, should I just give up on the Bionx motor and buy a generic Chinese one that's easier to hack?

I appreciate any help that you can give. I took this on as an interesting little indoor winter project and to begin to learn about ebikes but, to be honest, I really don't know what I'm doing.

So, the battery initially tested at 3v which is pretty much dead. I tried hanging the bike up and turning the pedals but that didn't help. So I dabbed it with an 18v drill battery (probably not the safest thing to do!) until it got over 17v and would accept the charger which I then left on for several hours. Several days later it still shows 55v when I first put the tester on, settling down to 40v after a few minutes.

The bigger problem now is that the square chip in the bottom row appears to be blown. It has discolored patches on top and there was a bit of black soot on the silver canister beside it. I heard a "pop" when testing the motor and the display turned off and won't turn on again.

Everything I've read says that the Bionx is very proprietary. They no longer carry parts or support the older models with the I2C bus. Even their diagnostic equipment now only does the CanBus! So I'm left trying to "hack" it to accept 3rd party controller, computer, battery, etc. Is it realistic for me to try to do this? I have very little knowledge in this area and while I do enjoy puttering with it I find I'm very quickly out of my depth. No, I'm not going to install an Arduino computer, whatever that is, to talk to it!

But I like the bike it's on (Miyata Triple Cross) so maybe I should just strip off all the Bionx stuff, try to find it a new home, and use the proceeds to buy myself a new back wheel?
What do you think?

I don't know enough about the BionX ssystem to say if the battery PCB is required to operate it or not. You can always try bypassing it. There's a number of threads around here about various versions of these systems that have good info in them if you poke around for BionX.
https://endless-sphere.com/forums/search.php?keywords=BionX&terms=all&author=&sc=1&sf=titleonly&sk=t&sd=d&sr=topics&st=0&ch=300&t=0&submit=Search

If all else fails, you could use an external controller to run the existing motor. The new controller's display, throttle, PAS etc., would all replace the BionX ones, and wouldn't feel the same but at least you'd be moving. There's a few threads about that sort of thing too, like this one:
https://endless-sphere.com/forums/viewtopic.php?f=30&t=90037&hilit=BionX