RN52 spontaneously went into firmware update mode

[NeilR]

Hi.  I have a v3.2 BlueSaab which stopped working.  When I pulled it from the car and applied 12V, the BT1 and BT2 LEDs flashed together three times (not alternately).  This apparently indicates the RN52 is in firmware update mode.  I did not do anything to put it in that mode.  I couldn't get it to do anything else, so I attempted to update the firmware.  It failed several times with communication errors but then suddenly the LEDs flashed alternately meaning it was trying to connect to another Bluetooth device.  I was able to pair with it, then I put it back in the car and it worked briefly, then stopped working again and is showing it is again in firmware update mode.  Any ideas why it might be flaking out like this?

[Mārcis]

Hello. The RN52 needs to have 47k resistor between GPIO3 pin and GND otherwise that pin will be "floating" it can fall into DFU mode. To update firmware the GPIO3 is HIGH at boot time (this is done by getting 5v from usb in BlueSaab board).