sleep busy loop

Hi,
We have a problem in our modules - ~5% of the modules do not start advertising right when the battery is inserted, and reset is needed - i.e. removing the battery and reinserting it.

We were advised to add the following line at the beginning of the main_func(void) in arch_main.c:
SetBits16(BANDGAP_REG, LDO_RET_TRIM, 0x08);

This did not work, so we were also advised to add a ~100ms sleep beforehand.
我知道如何使用app_easy_timer当应用程序是俄文nning, but I think it should not be used in main_func(void) - the data is not initialized for that....