https://devzone.nordicsemi.com/f/nordic-q-a/11465/bootloader-fails-after-power-cycleOk, this one seriously has me stumped... I have a custom bootloader that is modified from the DFU example (SoftDevcie S110 8.0, with SDK 9.0, using gcc). BLE is not used, it is pretty simple actually in that it just checks external SPI flash for aen-USTelligent Community 13Fri, 22 Jan 2016 12:06:35 GMThttps://devzone.nordicsemi.com/thread/43276?ContentTypeID=1Fri, 22 Jan 2016 12:06:35 GMT137ad170-7792-4731-bb38-c0d22fbe4515:e21e7e42-2f5f-4cbc-8218-ea9ffe79442cHung Bui<p>Hi Eric,</p> <p>I don&#39;t know what could be wrong neither.</p> <p>But could you clarify that with your &quot;new bootloader&quot; even if you don&#39;t do anything ( don&#39;t update application firmware)and simply do a power reset caused the issue ? I would suggest you to do a flash readout using nrfjprog, before and after you do a power reset. You may want to read the UICR out and compare as well.</p> <p>You can also try to run in debug mode and put a breakpoint inside the Reset_Handler of the bootloader. I suspect that the MBR didn&#39;t forward the PC to the right place.</p><div style="clear:both;"></div>