Not sure the MCB damaged or not

I tried to connect 3 SG90 servos to sonar p702.I plan to use GOIO 4, 17,18.I tested on the raspi and they works.
While I’m stupid to put p702 not the right way up,I treated pin50 as pin1.
After Power on, I heared a crack noise and there is a burning smell.So I cut off the Power immediatly.
I took off the raspi and found i’m not able to enter the system,with low voltage error.
I didn’t have another raspi beside me to test whether the robot board is working or not.
So frustrated…
In case there is any damage to the board, is it easy to repair or change a new one, and how much it would cost?I’m in China.
Thank you.

We have been very careful to use ‘keyed connectors’ wherever we can. P702 is a very tricky one because the raspberry Pi does not have a key and are just straight pins.

I see your followup post and will read that next.

Please tell me if you were using your own ribbon cable connector or something else or if it was the raspberry Pi itself that was plugged in in some way not correct?

We are trying different things to keep raspberry Pi from being off to the right or the left but I am not sure if that was what happened in your case.

Thank You,