iPhone 7 software problem iTunes (-50)

Hey guys,

just over night my iPhone is showing the apple logo (contonious, no blinking). I tried:

-new battery

- hard reset

-recovery mode

-DFU Mode

Just the DFU Mode helped a little bit. But in the end, it shows three different failures

- iTunes failure nr -50

-iPhone can't be identified

-iPhone can't be activated, because the iPhone doesn't send an activation information (i don't even know what that means :D)

Sometimes i can connect the iPhone with iTunes and it recognized the iPhone, but the display continious just shows the apple logo.

Thanks in advance for help.