Hi we are trying to test the serial boot loader example from sdk 11,sdk 12.03 non of them working while running using nrf go studio it says enter in dfu mode and while we used nrfutil command as given in the info centre it didn't work we tried with nrf51 and nrf 52 for nrf 51 we used sdk 11 and nrf 52 tried with sdk 15 secure boot loader Please help urgent