was driving with my b18 turbo last days.
Car is running on P28 with S300 without issues.
Out of sudden engine died and did not restart anymore.
Ecu fuse tripped and was replaced.
Ecu is now up and running again, S300 is working.

Unfortunately this is only working for some seconds, then the main relay starts clicking and car won't start up anymore.
I have traced down the issue to the DC DC converter in the P28 labelled with IC12.
It is getting really really hot and then the main relay starts clicking.

I have got another P28 here which does not have the same symptoms.

I have not found any broken capacitors or signs of damage within the Ecu.

I have attached a link to a video showing the normal behavior while starting ignition and then the clicking.
Has anybody an idea what could cause this?

 

I suggest checking the components installed for the Hondata. Make sure all the soldering was done well.
Also, when you tested the other P28 did you have the Hondata installed?