nRF52-DK Non-responsive

Question

I have been using a NRF52-DK board to develop a BTle solution for the past week. Today, midway through a debug session, the board vanished from my BT interfaces. It also no longer shows up on USB when plugged in, neither directly or when attempting to put into DFU mode (holding the reset button down and powering on over USB). Is there something in software I can do, or is this a hardware fault somewhere? 
 LED5 is not on. Nothign is seen on USB.

Asbjørn · Accepted Answer

Hello Emlyn, 
 
 The HW files schematic and layout are available here: https://www.nordicsemi.com/Products/Development-hardware/nRF52-DK/Download?lang=en#infotabs 
 My bad for making the assumption you had these already, sorry about that. 
 
 What you seem to have measured across R9 and C35 is what I expect. 
 
 Across C36 you measure 0V on both sides, this is not what I expected. It means the USB regulator on the nRF5340 isn't on, indicating the ODB is missing somehow. 
 
 If I understand this correctly, you've been in touch with DigiKey about this already. Contact them with regard to replacement in this case.

Best regards 
 Asbjørn

PjGlasso · Answer

That LED5 has me curious... 
 So I know you said no switches have moved but seemed as though it failed suddenly and unconventionally. That in mind, I 'll post these things to try if you want and others have found them useful. 
 
 Since the interface MCU (OBD) is unresponsive, the only ways to access or recover the board are:

Bypass the On-Board Debugger via External J-Link (Target Direct SWD):

If the main nRF52 target application chip is fine, bypass the dead nRF5340 debugger completely.

Connect an external standalone J-Link programmer (or another working nRF52/53 DK operating as a debug probe via Debug Out ) directly to the SWD header pins ( SWDIO , SWDCLK , GND , VTG ) routed to the target chip on the DK.

From there, issue a standard recover command targeting the external probe:

ok nrfjprog --recover -f nrf52 
 2. Isolate Hardware / Power Faults on the DK:

Power Supply Mode: Ensure the power source switch (SW10) is set strictly to VDD or USB depending on which port is plugged in.

Cut Straps & Switches: Double-check that no trace cut-straps (like nRF_POWER or SWD ) were modified or bridging adjacent traces.

USB Controller Reset: Disconnect all power, hold down the RESET button, and plug in the USB cable. If the board was stuck in a degraded power state, this can occasionally force the nRF5340 OBD back into a valid boot state.

3.... RMA / Replacement: If the nRF5340 interface MCU suffered an ESD strike or flash corruption on its USB stack (hence brief flash of LED5 before shutting off), Nordic support typically treats the kit as damaged hardware requiring an RMA replacement. 
 GL :-) PJ :v:

nRF52-DK Non-responsive

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