check for null in response for no Pi Zero 2

main.c

@@ -27,12 +27,12 @@ int main(int argc, char * argv[]) {
   const char testStr[] = "cat /proc/cpuinfo | grep 'Revision' | awk '{print $3}' | sed 's/^1000//' | grep '902120'";
   FILE *file_test = sopen(testStr);  // see if Pi Zero 2  
   fgets(resbuffer, 1000, file_test);
-  fprintf(stderr, "test result: %s\n", resbuffer);
+//  fprintf(stderr, "test result: %s\n", resbuffer);
   fclose(file_test);	
   
-  fprintf(stderr, " %x ", resbuffer[0]);
+//  fprintf(stderr, " %x ", resbuffer[0]);
-  fprintf(stderr, " %x ", resbuffer[1]);	
+//  fprintf(stderr, " %x ", resbuffer[1]);	
-  if (resbuffer[0] != 0) 
+  if (resbuffer[1] != 0) 
   {
     sleep(5);  // try sleep at start to help boot
     voltageThreshold = 3.7;