Accidentally connected module RX to controller RX --> magic smoke

[Fredrik_Viberg (FredrikV)]

Hi, I recently picked up my diybms project again after a long pause. I had a working controller board v4.2. But while fault searching one one of the modules (v4.4) I accidently connected RX to RX.

Some smoke was released from behind the screen on the controller. After, the screen is black and the ESP32 just has a red light which always stays on. I need some help assesing the damage.

I found an older post mentioning a similar accident.

DIYBMS v4

Uggh. I was trying to troubleshoot my modules, and must have accidentally switched RX and TX cables on the controller board. It released the magic smoke. Seems to have fried the board, ESP32, screen, and SD card. It’s such an easy thing to do, it sucks the cost is so high. Can I suggest a different cable connector for future revisions so nobody can make this costly mistake?

It mention that the ESP32 was and screen was dead. I guess I can just source new parts for those.
But I am trying to identify which of the component from the board which was caused the smoke.
Which component on the controller board is most likely to have burned?
I cannot see any obviously damage components.
Hate to just throw the hole board away.

Help appreciated.

edit: is there a danger to connecting new ESP boards or SPI screen to test if they work unless I have identify what component has failed on the control board?

[Fredrik_Viberg (FredrikV)]

After closer inspection it looked like both the SN65HVD75DR and TCA6408APWR has erupted. I think the screen is ok. The ESP32 has is recognized by the computer but does not respond on serial communication.

Switching to my spare board. Which seam to have some problem when I connect the screen for some reason. Have to continue fault searching.

Probably best option for the smoked one controller is to desoldering the bigger components (relay and connectors) to reuse on something else.