@mfalkvidd, I checked using the multimeter. In diode mode, I have 400 ohm between fdti and vcc. When powered a 0.4v drop. So both vcc's are not direct connected. Still strange it works OK with the 4.4v on the radio and not with 4.9 At least we have now an idea what It's a deek robot clone. https://arduino-board.com/boards/dr-pro-mini

If you need SMS/GPRS the following boards would be great, http://imall.iteadstudio.com/development-platform/arduino/arduino-compatible-mainboard/im130514001.html http://imall.iteadstudio.com/development-platform/arduino/arduino-compatible-mainboard/im120411004.html Both also have the nrf24l01 adapter builtin for you MySensors network.