All an all , there was something to be learned from this post:
1-know when and how to test the ATMega328 digital outputs. (I use a walking bit sketch that cycles all the outputs one a time from H to L and then back to high and repeats on all the outputs. It's a test setup on a breadboard with leds connected to the outputs. I have a 28 pin ZIFF socket
I have a 100k pot with a knurled knob connected across +5V and GND with a wire from the wiper to plug into the analog inputs when I want to test those.
2- When interfacing the TC4427 to an arduino, if the output won't turn off, first try the easiest solution, which is a pulldown resistor on the output of the ATMega328 (the TC4427 input)
3- Configure outputs as outputs if you intend to use them as such.
So, back the IRF3205.
Is it , or is it not turning OFF now ?
As I recall, this was the original issue.
Were you able to turn off the mosfet by just grounding the gate ? (not using the TC4427)
Were you able to turn off the mosfet with the TC4427 after you got the led to turn off by replacing the
ATMega328 chip ?