The current draw from the 3.3V output is 100 mA max and should be OK.
What have you done to test @groundFungus suggestion that you are overwriting memory?
If nothing, try
buffer[ind] = mySerial.read();
ind++;
if (ind > 24) {
Serial.println("array bounds violation");
ind = 24;
}
Use code tags when posting code, so it looks like the above.