Xerox WC5745 not booting. After power on machine display screen goes to green screen with Xerox logo and machine freeze. After 15-20 min on screen appears message " Communications error" I tried Atboot and forced Atboot but without success. Iniatially on screen apears firmware upgrade screen. When upgrade is complied I removed USB flash drive and pressed 0 button. Machine goes to rebboot and also freezes on green screen with Xerox logo. I replaced software module from working machine and bad machine start to boot and completed boot procedure. I installed new software module but machine still freeze and goes to "Communications error" I tried both Altboot and forced Atlboot but also without luck. What could cause new software module dont start?