Intermittent Flashing folder on startup

[Enthuser]

i understand that this means no OS can be found on a 5,1 2010. There is High Sierra installed on the hard drive but it normally will not boot on this machine after the chime. It does boot on a different machine with similar configuration. Any ideas what to check next? Thanks in advance.

 

[tommy chen]

wrong bootrom

can´t access to APFS drive

use a clear drive - install the macOS with a fullinstaller of sierra
then update to highsierra with a fullinstaller to get the firmwareflash