First, the circuit looks all right (see *), so are you sure it was assembled according to the diagram?
This microcontroller can be easily damaged by reverse polarity voltage, for example when Vcc is mixed up with GND, let’s hope this hasn’t happen ..
Second reason, still from the same category, is exposure of any pin to to high (Vcc+0.5V) or to low (Vdd-0.3V) voltages ..
(*) Looking at the component list, the 1N4942 diode that protects the /INT0 pin is not properly selected ..
Instead you should use a Shottky diode (Vf<0.3V) and if V[+] is higher than 5Vdc add a 4.7V Zener diode, too ..
If, while programing the microcontroller, everything went OK -- re-program it and try again, otherwise you’ll have to use new IC ..
IanP
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