Sorry, "didn't work" and "does nothing" are a bit non-specific.
Is it stuck in a loop somewhere? Inside the oscillator function, or outside? If not using a debugger in the power-cycle case, perhaps GPIO or UART to waypoint progress into the code, or common places where it goes to die.
If you are running from the PLL, you can't change that on the fly. With STM32 parts you generally want to switch on the secondary clock source, and then select that, along with speed appropriate flash/bus settings. Change the PLL settings, and bring that back up, before switching to it.
For other clocked peripherals you'll have to revisit the baud rates, dividers, etc.
The HAL is a bit bloated, I'd expect you'd need to stage through HAL_RCC_OscConfig() several times to get from A to B, but at register level it might be easier to manage.
void Error_Handler(void)
{
// Place to silently die
while(1);
}
void HardFault_Handler(void)
{
/* Go to infinite loop when Hard Fault exception occurs, die quietly and hope no one notices */
while (1)
{
}
}
I find it more enlightening to output actionable diagnostic data so I can root-cause the failure
