I've attached 12V instead of 5V PSU by occasion.
Is there any chance to restore the board?
The schematic for the H3 starter kit is available here https://www.renesas.com/us/en/doc/products/rcar/R-Car_StarterKit_Gen3_SCH_Rev.110.pdf. If you're lucky, then maybe you've just damaged the PMIC. However, it seems that there's just few info too available in public regarding the PMIC used in H3 starter kit. If you can't really figure out how to repair it then I suggest submitting a ticket to Renesas Technical Support.
JBRenesasRulz Forum Moderator