i can't get out of TWRP recovery mode

Hello,

I'm a newcomer in this forum but I have already successfully unlocked bootloader and flash custom rom onto my OnePlus One.

Now I'm doing this for my friends Xperia Z as well but i'm stuck in recovery mode now.

This is what I've done so far:
- unlock bootloader
- flash twrp image file via fastboot
- after command "fastboot reboot" -> it boots into twrp recovery
- asks me if its okay to modificate system partition, i swipe okay
- want to reboot into system -> asks me if i want to flash supersu for root access, i swipe okay
- boots into twrp recovery -> want to reboot into system but i boot into twrp anyway

Edit: when power down the phone and restart -> boots into twrp recovery

Now I'm stuck in recovery mode. Please help me

raichisaku