After getting so many suggestions, I'll summarize into this list.
1.Even if the cart isn't bricked (which I doubt by everything it was sad) the time and effort necessary to revive it it's worth in my opinion.
A few ways you can try.
Getting SPI Flasher, it isn't cheap and will require you some technical knowledge and specific files to specifc carts.
Trying putting r4 firmwares one at time into your sd cart and give them a run, hoping to find one it works.
(again there are many firmwares out there, it may take a while and it's not guaranteed that will work.
The cart used to work with the original firmware you have bkp and it doesnt work anymore, so trying different ones its a very very long shot)
2.Try to buy a new FC (today it is gamble because so many counterfeit/bad carts out there)
3.Get a mini sd adapter + micro sd card OR mini sd card to make use of camera glitch to run your games. (best and cheap solution)
To help others and peharps yourself you could post photos of you FC (front label) and PCB (front/back)
So people would know to not do the same thing you did with this cart.
And someone who has the same can point out the correct firmware.