[Q] Shutdown makes my phone unable to boot without PC

Hello,

I got a weird problem after unlocking my phone's bootloader and flashing the kernel:

When I power off the phone, it gets into a state where I cannot control it by itself (black screen, no charging light if connected to a power source, does not react in any way to any key).
However, I am able to access it via adb over USB. Using adb, I can put it into some other state (reboot, reboot bootloader, etc) and again gain control over it (also through its own keys). When I select the "power off" function of the bootloader, it enters this state again.
I can even reboot the phone (also into recovery/bootloader/fastboot) from any state

So I can use the phone, but I can't power it on by itself, which isn't a good situation when I don't have a computer around.

device: HTC One S
ROM: CyanogenMod 10 (device is officially supported by CM10; I used the version I found in the Wiki.)
kernel: The one included in CM10 (had to be flashed manually via fastboot because of restrictions by the device; I flashed the kernel before flashing the ROM)

Does anyone can tell me something more about this (or even a solution)? I don't even know how to call this state ;)