A few days ago, my wife went to start the dryer and she heard a pop and it threw a F01 code. Looking online, it said it was the main control board, which I removed and saw a huge black spot on the bottom, so that was it.

I bought a replacement and just put it on, but now I'm getting a F70 code, which means the board isn't communicating with the user interface board.

Before I buy one of those, I'm wondering if I got a bad replacement board. I'm thinking not because I'd still be getting the F01, correct. I looked at the user board and the connections are all good.

Anyone ever had a similar issue?

Model is WED9500TW2

Following because I'm doing the same repair tomorrow for a F01 code.

Guessing from a HVAC similar problem.
Outside unit control board was fried but caused by something else, so replacing just the board w/o solving the cause wouldn't fix it, said the repairman with decades of experience.

On the other hand, a tree fell on backyard power lines = fried Washer Ctl.board = $$$$
In that case, replaced board & all fixed + added a surge protector to its outlet. Perhaps wrong board was sent you?

The sequence of the repair posted on Fred's Appliance supports tgi's initial comment that the main board could have blown due to another issue as Fred says to replace the user interface board first.

https://fredsappliance.com/dryer-repair/how-to-fix-whirlpool-dryer-f70-error-code/#:~:text=What%20Does%20the%20F70%20Error,be%20able%20to%20work%20properly.

However, this seems to be a common problem. Here's a video showing a successful(for the moment anyway) DIY repair on a blown main board. Did yours fail in the same location? Have you researched putting the dryer in diagnostic mode and running some tests?

I ask because I had an issue last year with our 16 year old Fisher Paykel washer and placing it in diagnostic mode and running some tests helped diagnose the problem.

Also where did you source the main board? I bought a refurb(with 1 warranty) at https://www.partsimple.com/ They also took my old board back to refurb which was cool.

Yeah, my main board failed at the same spot and the black spot looked pretty identical to the one in the video. I found a used interface board for my dryer on eBay for like $35, so I'm going to try that. If it doesn't work, I may call someone, or buy the wife a late Christmas present.