@luchangtzudir going with the assumption that your battery is good and working and everything else is installed as is, I would suggest that you check the fuse on the main board. F1 is the power fuse and if that fuse has blown, the power can't be turned on. The fuse is a 32V 2A SMD fuse and you just need a multimeter and check the fuse for continuity.
If that should be okay, then you most likely have an issue with the DC-DC board. It's a bit tougher to fix ;-)
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