Acrylic Prusa I3 PRO B 3D Printer DIY kit

Hi, i have a porblem troubleshooting behaviour problems. My Printer doesn't accept movements to the left. After Powering on, it sometimes does, but then only accepts Movements to the right (for example X +10) after that, it doesn't go back left (says "X_min triggered"). This is the case with the Y axis, too, most of the time._br_M114 says X0 Y0 Z10 (Z actually is at 10)._br_M115 gives back Marlin 1.0._br_I can't update the firmware, the process of updating the firmware seems to stall without giving any error message (update had been running _60min)._br_Please help!