nRF52 DK not working/powering up

[Muzammil]

I have couple of nRF52-DK boards which I think got damaged by accidentally getting reverse voltage.

I have tried to analyze and detect which part would have blew up by testing the pins of different parts (Looking through the schematic and side by side testing on a working nrf52-DK board), which by understanding would be the LDO (AP7333-33SAG-7), ESD Protection Diode( PRTR5V0U2X ) , Schottky Diode( SD103ATW-7-F) or the Micro (ATSAM3U2CA-AU).

Modifications were made on 2 boards as following-

1. On first board output of LDO was as low as 1.2V  when the board was powered up. I replaced it with a new one but still the board was not able to power up. One of my colleague tested the board and suggested that the micro might have blew up, So I changed the micro too and still the board was not working. Other things that I noticed is the board is not visible on device manager at all.

2.  On second board the ESD Protection Diode showed that the pins are shorted and the LDO. I changed both the Ic and measured the outputs which gave the respective results, but the board was still not working. Other things that I noticed is the board is visible on device manager with the name -Bossa Program Port.

I have also tried to follow these steps except step-4 and these but still was unsuccessful.

Is there any guide which I could follow to get my boards working and a guide how to program the boot-loader of the micro.

Any help is much appreciated.

Thanks 

[Stian Røed Hafskjold]

On the DK where you have the Bossa program port you can try to load the JLink interface FW using this guide: https://wiki.newae.com/Manual_SAM3U_Firmware_Update 

Other than that the schematics of the DK can be found here: https://www.nordicsemi.com/Software-and-Tools/Development-Kits/nRF52-DK/Download#infotabs

[Muzammil]

Hi @Stian,

I followed your step to load the JLink interface FW through the link provided, which showed that the interface FW was flashed successfully and I verified it to, but now after restarting the DK its not at all showing on device manager, nor as a JLink device. The supply of the board is all working.

Now both the boards are not visible at all on device manager.

Do you think the Micro should have been flashed via a tag connector on to -

Is there any other way to debug the hardware via any test points?

All of my testings are referenced through the DK schematic provide by Nordic.

Thanks

[Stian Røed Hafskjold]

A long time ago I was experimenting with this and I had success in flashing the ATSAM micro with the pins in the picture you posted. The ATSAM was completely erased and I flashed it with the bootloader in this git repo: https://github.com/NordicPlayground/CMSIS-DAP Unfortunately I couldn't find the hex.. But there are project files for Keil, so you should be able to compile it.

[Muzammil]

I tried CMSIS-DAP repo to build the bootloader via keil, which did build up ,but  flashing it with a working nrf52-DK didn't work, I think I needs JTAG Probe to flash it.

I also tried this and this method by Gaute Gamnes which wasn't a success as well.

Also what do you think might be possible gone wrong on the hardware side?

[Stian Røed Hafskjold]

Sorry, I don't know really. At some point I think we just need to accept that the HW is broken and get a new one :)

[Muzammil]

I think that's what I have to do, Thanks for your help.