Camera won't turn on, keep indicate low battery

So the day before I had to shoot wedding, as usual I did a camera test and suddenly the camera turned off, I don't know what happened. it only indicates low battery through the viewfinder.

oh maybe I didn't fully charge it!

charge it back, doesn't work!

oh maybe my battery is leaking/damaged!

tried my other battery, still doesn't work!!!

oh maybe my charger is broken!

bought a new charger, still doesn't work!!!!!

oh maybe both of my batteries are leaking/damaged!

bought a new battery and still doesn't work!!!!!!!!!

and I have to rent a camera to shoot the wedding. The camera is about 7 years old and I checked the shutter count around 75k. I hope someone can help me with this, whatever it is will be appreciated. Thank You