I recently bought an arduino uno r4 WiFi and didn’t know the maximum voltage the VRTC could handle and connected a battery to it ,immediately there was a small fire on the board but I can’t recall exactly where because I was busy unplugging the battery , the board’s software which I last programmed was working fine but when I connected a computer to it ,it didn’t show up on the device manager with no signs of anything plugged in (the power led works fine along with the L reset one) I tried changing the esp32’s firmware but after I short the pins still nothing shows on the computer (no notification not on the device manager too) how do I fix this and what components do I need to replace or should I buy a new one
A fire? I think you already know what the answer is. You now have an expensive paperweight. Buy another R4 and observe the maximum Vrtc next time.
The UNO R4 WiFi features a VRTC pin, that is used to keep the onboard RTC running, even when the boards power supply is is cut off. In order to use this, apply a voltage in the range of 1.6 - 3.6 V to the VRTC pin.
Best to buy another board. You might damage your PC connecting it to the dead one, depending how far the overvoltage destruction progressed.
The best thing you can do is order another one, frame this one to remind you to read all of the instructions before connecting anything to it. Then double check the wiring before powering on.
did you do it by accident or for science?
accidents can happen, exploring something's limits is honourable.
if you did it thinking it would be ok then you should have done some research first 
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