First, there is a registry key you can check:

[HKEY_CURRENT_USER\Performance]
"Last Boot Type"=dword:00000002

after a coldboot this value is 0. For warmboots the value is 2.

and another one

[HKEY_LOCAL_MACHINE\Comm]
"BootCount"=dword:00000005

The BootCount value starts with 1 at a cleanboot and counts with every reboot. This device had 1 clean boot and 4 warm boots.

These registry keys are easy to find with free tools like ssnap and WinMerge.

Another way to check for a clean boot is to look for a custom file or a custom registry entry in \Windows. With a cleanboot all contents is reset to the factory default (except for \Flash File Store (persistent storage) or external memory cards). If you created a file in \Windows or a value in the registry, these are gone after a cleanboot.

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SetSystemPowerState(NULL,POWER_STATE_RESET,0);

Using KernelIOControl to reset a device (warm or cold boot) may not flush buffers to storage and so the article shows how to use SetSystemPowerState to reboot a Windows Mobile device.

I recommend all to use SetSystemPowerState to reset a WM device instead of using KerneIOControl to avoid missing data. SetSystemPowerState with argument POWER_STATE_RESET will first flush disk buffers and then perform the reset. This will be much safer than doing it the ‘hard way’ with KernelIOControl.

see also here and at MSDN and this great article at CodeProject

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