Rancher VMWare Guest does not boot

Hi all,

I have a problem with a rancheros 1.5.6 VMWare Guest that does not boot anymore. I have now booted with rancheros-vmware.iso in recovery console and mounted the first harddisk. How can I re-write MBR?

Should there be a /boot directory on the first disk?

I also saw that the person who installed it did not create partitions but used whole disk for filesystems.

Any help is appreciated.