How to flash bootloader to thingy 52?

[Gova]

I am a newbie for Nordic development boards. I recently bought a thingy 52. When I was searching for how to upload a custom firmware of my own (After disabling few BLE services), I came across this link. OTA-DFU - Generating your own packages

I have installed nrfutil and have generated Private key. But how am I supposed to flash the bootloader? I have only one thingy board in hand.

Once I have my ZIP file, I can do a OTA-DFU with my phone. But please let me know how to flash the bootloader onto the board over the air.

I would be glad if someone can help me. Thanks a ton in advance.

[Gova]

Thank you so much for your reply. Yes with the attached images, I think i need a nRF DK to program the bootloader.

[Bjørn Kvaale]

Edit: This was wrong unfortunately. You need to use Secure DFU to upload custom FW to the Thingy.

[giova]

Hi, is it possible to upload your own custom firmware using OTA only(no DK) to a device which is flashed with a bootloader and app signed using the Nordic private key?

I tried but I always get error INVALID_OBJECT ...

[Bjørn Kvaale]

Hi Giova, you can upload your own custom firmware over the air, once you have generated a new public & private key & installed your own bootloader (see link). If you know the Nordic private key, it should work to upload custom FW to a device flashed with bootloader & app signed using the Nordic private key. But since you do not know the Nordic private key, this is most likely the reason you are getting this error. You will unfortunately need a DK or an external Segger J-Link to be able to erase & program the Thingy:52 device the first time with your own bootloader.